This graphic analysis was done by Peter Chandler of the Institute of Ocean Sciences.
Category Archives: Education
Humpback Whales Feeding off Race Rocks
There has been 2 humpbacks hanging around the Becher Bay – Race Passage for the last couple of weeks. They have always been a little bit distant from the Lighthouse, but on December 30th 2020 they came right up to the SW corner of the lighthouse and did some feeding right at the current line. There’s lots of turbulence, so it could be some bubblenetting or lungefeeding. Really cool to see them use the crazy currents around Race Rocks to get a meal in.
Elephant Seal Pup Growth – Day by day
The first Elephant Seal pup of the 2021 birthing season came on December 22 2020, and began it’s 23 days of nursing the day after (it took him awhile to figure out how to nurse). Elephant seal pups only have a couple of weeks to get big enough and healthy enough to survive alone after their moms wean them and abandon them on Race Rocks; which means their life is essentially just to feed, nap, and snuggle with their moms. It’s hard to show how impressive it is to see how fast they put on weight, with the pup doubling in size over the first few days. Here’s a video of the growth of ‘Cheermeister’ over his first 12 days of life.
https://youtu.be/ltMsnNRYTmU
Also see other posts on elephant seal pups born at Race Rocks, the most northerly pupping colony for e-seals on the Pacific coast: https://www.racerocks.ca/tag/pup/
The Problem with Ocean Fouling/succession-
When installing equipment underwater in a high current zone where the water is laden with nutrients from upwelling as it is at Race Rocks, it becomes obvious very soon that any new substrate placed underwater becomes an instant habitat for the settlement of many invertebrate and algal species. For this page I have brought together different examples from the work we did over the years at Race Rocks. . It should be noted that the word “fouling”is a rather perjorative term, seen from the point of view of a natural process interfering with human wishes. However, it simply represents ecological succession, a perfectly natural event in a highly productive environment, and too bad that it inconvieniences us!
This video from 2001 shows what the condition of the growth of life was on a sensor bar that we installed in water at 8 meters depth just off the Jetty at Race Rocks: The sensors were for monitoring Oxygen, salinity, ph, and turbidity. Without constant attention by our divers getting accurate data from sensors like these over a long term would not be possible. This video was taken after three months in the water .
In September of 2011 we ended the experimental Tidal energy Project at Race Rocks. This file has images of the turbine covered in fouling organisms when it was raised for the final time:
Examination of the tidal energy installation after being installed for 6 months
The engineers concern for the kind of materials they were going to use in constructing the turbine were addressed by having the Pearson College Divers install a series of succession plates that could be monitored for growth over several months.
Video inspection done by Chris Blondeau on turbine inspection before removal, June, 2011 The growth of Invertebrtates is quite incredible. Since ther is little opportunity for predators like starfish to browse on this column, growth is unimpeded. This led us to decid that the i meter wide .. 15 metre high column should remain in place after the turbine was removed as such it has turned out to be such a unique habitat.
Another example of succession is evident in the way that kelp attaches to a solid substrate and can end up in modifying the environment. In this case moving rocks from ocean to shore.
Measurement Exercise
Today we had a request from Meghan Byrne, a 6th grade science teacher in the San Francisco Unified School District. She was doing a lesson with her students on size and scale and she was interested in using the following picture from this blog of the elephant seal measuring device – and letting students determine its length.
So I thought that would be a good exercise to include here for school students. Ecoguardian Mara has provided the following photos of the boat ramp rail so you can now calculate the length of the small elephant seal.
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- full measuring tape in cm and inches
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- start of the tape
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- ending of distance on the tape
Be sure to calculate the length of the Elephant seal in both centimeters and in inches. Then you can also convert it to Metres and Feet .
Mara sent another picture of a larger male, the brackets on the rail can just be made out so calculate his size.
Pearson College Student Field Trips to Race Rocks
This file is an index to the Student Field trips to Race Rocks after 2010. Most of the Events posted here are in links to the blog created by Laura Verhegge to document some of the field trips taken by her Marine Science classes
For other tagged occurrences of Pearson College students being involved at Race Rocks documented here use this link:
EVENTS 2018:
Four Trips to Race Rocks in Three Days-Laura Verhegge Oct 2018
Northern Elephant Seals at Race Rocks.. The First Year Field Exam, 2017
there were 11 northern elephant seals (Mirounga angustirostris) that provided both entertainment and answers to the students writing the exam.
Field exam at Race Rocks 2016
On Monday 9 May, 26 Marine Science students travelled to Race Rocks on Hyaku or the Discovery Shuttle (chartered from Ocean River Sports since ‘Second Nature’ is still in the shop) to write their first year field exam.
Sea lions, seals and orcas, oh my!
First year marine scientists had a wonderful experience at Race Rocks on Friday September, 2016
Also: Orcas! The trip that never made it to Race Rocks
What a day for mammals!. September 30, 2015–
Later in the day, a first year class was welcomed ashore at Great Race Island by the usual suspects, California sea lions, Stellar sea lions and a Northern elephant seal
Race Rocks visits with Year 41 students
Three great afternoons at Race Rocks with the three blocks of first year Marine Science students – Tuesday, Wednesday and Friday. We observed and photographed many sea lions, both California (Zalophus californianus) and Stellar or Northern sea lions (Eumetopias jubatus).
Field May 19 2014 – A block
Better late than never, right? On 16 May 2014, the other class of first year marine scientists (A block) wrote their field exam at Race Rocks. Here are a few photos of their experience.
Field Exam 2014 – D block
It was a stunningly beautiful Thursday morning when eight D block marine scientists travelled to Race Rocks to complete their field exam.
Tidal pools and abiotic factors at Race Rocks
Baby is growing up fast.February 2014
One class of Marine Science students had the chance to visit a newborn Northern Elephant Seal pup when it was just a few days old, during our first week back in class, in January.
Pearson College Marine Science Blog by Laura Verhegge. Race Rocks exploration – 11 April 2013
Field exam May 2012
It was sunny and warm with a just gentle breeze yesterday when first year marine scientists went to Race Rocks to complete their last challenge of the year – the field exam!
CAS week
- 8 students and Laura, their instructor were here for the week.
- They carried out several interesting studies, including counting the sea lions 5 times/day, watching animal groupings according to the wind direction and intensity, keeping track of the tagged and branded sea lions to watch their movement.
- I was grateful for their help when I drove Laas to Pearson College in the whaler. The winch is much easier to use with several hands!
I’m Back
I am back on Race Rocks, this is my third year but I’m only staying for 3 months this time. I am very happy to be back and look forward to a beautiful and productive autumn.
Today I plan to take a good look around the island and see if any of the sea lions have any injuries and just do a good once over.
I’ve spent the last 5 months with the whale watching community and here are some things I have learned. The whale watchers care about these animals as much as I do and our goal is education. We enjoy sharing this beautiful ocean and our knowledge of these animals with other people. The observations I’ve made during this summer are that many commercial boats do keep a respectful distance. The whale watching boats actually help me out as an ecoguardian. There are plenty of areas in the reserve that are out of my sight and if they see an injured animal they notify me and tell me where it is so I can monitor it and let marine mammal rescue know. If someone is doing activity within the reserve that shouldn’t be like fishing or snorkeling in a dangerous area they let that boat know that they can’t do that. I have a very difficult time trying to get a hold of pleasure crafts because they are always on different radio channels so this really helps me when others look out for the safety of the reserve and others within the reserve.
This island is a special place for many people and so much goes into protecting this ecological reserve and I just wanted to acknowledge a group of people who have helped in many ways to protect Race Rocks.
Decade Comparisons:Sea Surface Temperature at Race Rocks-
Link to Race Rocks Mean Monthly Sea Temperature 1921-present,
| Monthly temperature averages in degrees Celsius for Race Rocks | ||||||||||||
| 1921 | 1922 | 1923 | 1924 | 1925 | 1926 | 1927 | 1928 | 1929 | 1930 | Average | Month | |
| Jan | 6.4 | 7.1 | 7.1 | 6.6 | 7.8 | 7.6 | 6.9 | 7.1 | 6.5 | 7.0 | Jan | |
| Feb | 7.1 | 6.1 | 6.4 | 7.3 | 6.9 | 8 | 7.4 | 7.3 | 6.3 | 6.6 | 6.9 | Feb |
| Mar | 7.3 | 6.6 | 6.7 | 7.7 | 7.3 | 8.6 | 7.8 | 7.8 | 7.1 | 7.1 | 7.4 | Mar |
| Apr | 7.7 | 7.5 | 7.6 | 7.9 | 8 | 9.2 | 8 | 8.6 | 7.8 | 8.2 | 8.1 | Apr |
| May | 8.5 | 8.3 | 8.6 | 9 | 9.2 | 10.1 | 8.8 | 9.7 | 9 | 9.3 | 9.1 | May |
| June | 9.5 | 9.5 | 9.3 | 9.8 | 10.1 | 10.7 | 9.8 | 10.2 | 9.8 | 10 | 9.9 | June |
| Jul | 10.3 | 10.5 | 10.3 | 10.5 | 11.1 | 11.1 | 10.5 | 10.8 | 10.8 | 10.6 | 10.7 | Jul |
| Aug | 10.5 | 10.3 | 10.5 | 10.3 | 10.8 | 10.9 | 10.9 | 10.9 | 10.8 | 10.8 | 10.7 | Aug |
| Sept | 10.3 | 10.2 | 10.6 | 10.2 | 10.2 | 10.5 | 10.3 | 10.3 | 10.7 | 10.6 | 10.4 | Sept |
| Oct | 9.8 | 9.3 | 9.6 | 9.2 | 9.2 | 9.8 | 9.7 | 9.2 | 9.8 | 9.4 | 9.5 | Oct |
| Nov | 9.1 | 8.4 | 8.7 | 8.8 | 8.3 | 9.1 | 8.6 | 8.6 | 8.8 | 8.6 | 8.7 | Nov |
| Dec | 8.2 | 7.1 | 7.9 | 7.3 | 8.2 | 8.5 | 7.6 | 7.9 | 7.8 | 8 | 7.9 | Dec |
| 8.8 | Decade average |
|||||||||||
| Average | ||||||||||||
| 1995 | 1996 | 1997 | 1998 | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | |||
| Jan | 8.2 | 8.2 | 7.7 | 8.7 | 8 | 7.5 | 7.9 | 8.1 | 8.8 | 7.8 | 8.1 | Jan |
| Feb | 8.6 | 7.8 | 7.9 | 9.2 | 7.8 | 7.7 | 7.7 | 7.9 | 8.5 | 7.9 | 8.1 | Feb |
| Mar | 8.8 | 8.4 | 8.1 | 9.7 | 8.1 | 8.1 | 8.1 | 7.7 | 8.7 | 8.3 | 8.4 | Feb |
| Apr | 9.2 | 9.2 | 9 | 9.9 | 8.9 | 9.1 | 8.7 | 8.7 | 9.2 | 9.1 | 9.1 | Apr |
| May | 10.2 | 10 | 10.3 | 10.4 | 9.5 | 10 | 9.7 | 9.4 | 9.9 | 10.4 | 10.0 | May |
| June | 11.2 | 10.4 | 10.9 | 11.4 | 10.4 | 11.1 | 10.6 | 10.5 | 10.9 | 11 | 10.8 | June |
| Jul | 11.8 | 11.5 | 11.7 | 11.7 | 11.1 | 11.3 | 11.3 | 11.2 | 11.3 | 11.8 | 11.5 | Jul |
| Aug | 11.5 | 11.5 | 12.2 | 12.3 | 11.5 | 11.7 | 11.4 | 11.7 | 11.4 | 11.9 | 11.7 | Aug |
| Sept | 11.3 | 10.5 | 11.6 | 12.1 | 11.9 | 11.4 | 11.4 | 11.3 | 11.4 | 11.2 | 11.4 | Sept |
| Oct | 10.2 | 9.9 | 11.3 | 10.7 | 10.1 | 10.3 | 10.2 | 10 | 10.9 | 10.6 | 10.4 | Oct |
| Nov | 9.4 | 8.7 | 9.9 | 9.8 | 9 | 9 | 9.2 | 9 | 9 | 9.4 | 9.2 | Nov |
| Dec | 8.9 | 7.6 | 9.3 | 9 | 8.5 | 8 | 8.3 | 8.8 | 8.5 | 8.6 | 8.6 | Dec |
| 9.8 | Decade Average |
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| This analysis has been done by Garry Fletcher using the monthly averages of the daily temperatures. See this file for the complete set of monthly data1921 to present |
 |
| The following is a comparison between 1951-1960 and 2001-2010
Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec 2001 7.9 7.7 8.1 8.7 9.7 10.6 11.3 11.4 11.4 10.2 9.2 8.3 Monthly Means
|
See also https://www.env.gov.bc.ca/soe/indicators/climate-change/sea-surface-temperature.html
Archive of Seawater Temperature Data 1921 to present
Note, The blanks for the years 1940-41 are due to the Second World War. Apparently during that time, data was not collected by a lightkeeper.Original data was sent by the Lightkeepers and now by the Marine Protected Area Guardian of Race Rocks to the Institute of Ocean Sciences where it is compiled and displayed at
http://www.pac.dfo-mpo.gc.ca/science/oceans/data-donnees/lighthouses-phares/index-eng.htm
Decade analysis by G. Fletcher.. NOTE probable evidence of climate change
Race Rocks Light Station: 48.2996 123.5318
| Year | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
| 1921 | — | 7.13 | 7.39 | 7.75 | 8.53 | 9.57 | 10.31 | 10.53 | 10.35 | 9.88 | 9.21 | 8.25 | |
| 1922 | 6.4 | 6.1 | 6.6 | 7.5 | 8.3 | 9.5 | 10.5 | 10.3 | 10.2 | 9.3 | 8.4 | 7.1 | |
| 1923 | 7.1 | 6.4 | 6.7 | 7.6 | 8.6 | 9.3 | 10.3 | 10.5 | 10.6 | 9.6 | 8.7 | 7.9 | |
| 1924 | 7.1 | 7.3 | 7.7 | 7.9 | 9 | 9.8 | 10.5 | 10.3 | 10.2 | 9.2 | 8.8 | 7.3 | |
| 1925 | 6.6 | 6.9 | 7.3 | 8 | 9.2 | 10.1 | 11.1 | 10.8 | 10.2 | 9.2 | 8.3 | 8.2 | |
| 1926 | 7.8 | 8 | 8.6 | 9.2 | 10.1 | 10.7 | 11.1 | 10.9 | 10.5 | 9.8 | 9.1 | 8.5 | |
| 1927 | 7.6 | 7.4 | 7.8 | 8 | 8.8 | 9.8 | 10.5 | 10.9 | 10.3 | 9.7 | 8.6 | 7.6 | |
| 1928 | 6.9 | 7.3 | 7.8 | 8.6 | 9.7 | 10.2 | 10.8 | 10.9 | 10.3 | 9.2 | 8.6 | 7.9 | |
| 1929 | 7.1 | 6.3 | 7.1 | 7.8 | 9 | 9.8 | 10.8 | 10.8 | 10.7 | 9.8 | 8.8 | 7.8 | |
| 1930 | 6.5 | 6.6 | 7.1 | 8.2 | 9.3 | 10 | 10.6 | 10.8 | 10.6 | 9.4 | 8.6 | 8 | |
| 1931 | 7.8 | 7.8 | 8.2 | 8.8 | 9.9 | 10.6 | 11.5 | 11.1 | 10.7 | 9.6 | 8.6 | 7.7 | |
| 1932 | 7.1 | 6.8 | 7.3 | 8.2 | 9.3 | 10.4 | 10.8 | 10.9 | 10.7 | 9.6 | 8.9 | 7.7 | |
| 1933 | 7.1 | 6.7 | 7.1 | 8 | 9.1 | 10.2 | 10.5 | 11.5 | 10.1 | 9.6 | 8.6 | 7.7 | |
| 1934 | 7.8 | 7.9 | 8.3 | 9.2 | 10 | 10.8 | 10.9 | 11.6 | 10.7 | 9.7 | 9.2 | 8.4 | |
| 1935 | 7.2 | 7.2 | 7.5 | 7.8 | 9.2 | 10.1 | 10.5 | 10.5 | 10.7 | 9.7 | 8.2 | 8.1 | |
| 1936 | 7.9 | 6.7 | 7 | 7.8 | 9.3 | 10.4 | 11.3 | 11.3 | 10.5 | 10.1 | 8.6 | 7.9 | |
| 1937 | 6.6 | 6.4 | 7.7 | 8.7 | 9.9 | 10.9 | 11.7 | 11.5 | 10.9 | 9.9 | 8.5 | 8.1 | |
| 1938 | 7.4 | 7.2 | 8.1 | 9.4 | 10.6 | 12.3 | 12.7 | 11.9 | 11 | 9.9 | 8.6 | 7.5 | |
| 1939 | 7.4 | 6.6 | 7.1 | 8.6 | 10.3 | 11.4 | 12.2 | 11.1 | 11.4 | 9.7 | –< | 8.5 | |
| 1940 | 7.98 | 8.28 | 9.06 | 10.09 | 11.49 | 11.69 | — | — | — | — | — | — | |
| 1941 | — | — | — | — | 10.87 | 10.54 | 11.29 | 11-05 | 10.66 | 9.97 | 9.07 | 8.60 | |
| 1942 | 7.9 | 7.9 | 7.8 | 8.5 | 9.6 | 9.8 | 10.5 | 11 | 10.3 | 9.5 | 8.4 | 7.9 | |
| 1943 | 6.8 | 6.7 | 7.1 | 8.2 | 8.8 | 10 | 10.3 | 10.6 | 10.3 | 9.6 | 9 | 8.1 | |
| 1944 | 7.7 | 7.5 | 7.3 | 8 | 9.2 | 10.5 | 11 | 10.9 | 10.5 | 9.6 | 9.2 | 8.1 | |
| 1945 | 7.8 | 7.7 | 7.6 | 8 | 8.8 | 9.8 | 10.1 | 10.5 | 10 | 9.5 | 8.1 | 8.1 | |
| 1946 | 7.7 | 7.3 | 7.7 | 8.1 | 9.4 | 10.2 | 10.7 | 10.8 | 10.3 | 9.4 | 8.1 | 7.7 | |
| 1947 | 7.1 | 7 | 7.7 | 8.4 | 9.5 | 10.4 | 10.6 | 10.9 | 10.5 | 9.9 | 9.1 | 7.9 | |
| 1948 | 7.5 | 6.9 | 7.2 | 7.9 | 9 | 10.2 | 10.8 | 10.7 | 10.4 | 9.5 | 8.2 | 7 | |
| 1949 | 6.1 | 6.1 | 6.9 | 8.3 | 9.4 | 10.1 | 10.3 | 10.2 | 10.5 | 9.5 | 8.7 | 7.8 | |
| 1950 | 6.2 | 5.8 | 6.6 | 7.7 | 8.7 | 9.4 | 10.1 | 10.4 | 10.3 | 9.3 | 8.5 | 8 | |
| 1951 | 7.5 | 6.9 | 6.7 | 8.1 | 9.2 | 10.2 | 10.4 | 11.1 | 10.9 | 9.5 | 8.5 | 7.7 | |
| 1952 | 6.9 | 7.1 | 7.6 | 8.2 | 9 | 9.6 | 10.4 | 10.5 | 10.2 | 9.8 | 8.6 | 7.9 | |
| 1953 | 7.8 | 7.9 | 7.6 | 8.1 | 9.3 | 9.8 | 10.6 | 11 | 10.6 | 9.9 | 9.3 | 8.5 | |
| 1954 | 7.1 | 7.3 | 7.5 | 7.9 | 8.7 | 9.3 | 9.9 | 10 | 10 | 9.4 | 9.1 | 8.4 | |
| 1955 | 7.5 | 7.1 | 6.7 | 7.5 | 8.4 | 9.3 | 9.8 | 10.2 | 10 | 8.9 | 7.5 | 6.6 | |
| 1956 | 6.7 | 6.4 | 6.3 | 7.6 | 8.7 | 9.6 | 10.2 | 10.4 | 10.1 | 9.2 | 8.1 | 7.1 | |
| 1957 | 6.3 | 6.2 | 7.2 | 8.1 | 9.3 | 10 | 10.3 | 10.5 | 10.5 | 9.8 | 8.8 | 8.3 | |
| 1958 | 8 | 8.3 | 8.6 | 9.3 | 10.3 | 10.7 | 11.5 | 11.5 | 11 | 9.9 | 8.7 | 8.1 | |
| 1959 | 7.6 | 7.4 | 7.9 | 9.1 | 9.7 | 10.4 | 11.3 | 11 | 10.4 | 9.7 | 8.3 | 7.8 | |
| 1960 | 7.1 | 7.5 | 7.5 | 8.6 | 9.6 | 10.3 | 11.4 | 10.8 | 10.1 | 9.5 | 8.6 | 7.9 | |
| 1961 | 7.9 | 8.2 | 8.4 | 8.8 | 9.4 | 10.3 | 10.9 | 11.3 | 10.6 | 9.4 | 8.2 | 7.5 | |
| 1962 | 7.2 | 7.3 | 7.3 | 8.4 | 9.3 | 10 | 10.4 | 10.5 | 10.5 | 10 | 9.3 | 8.7 | |
| 1963 | 7.5 | 7.5 | 7.8 | 8.5 | 9.6 | 10.2 | 10.5 | 10.8 | 10.6 | 10.3 | 9.9 | 8.7 | |
| 1964 | 8.2 | 7.9 | 7.7 | 8.2 | 8.8 | 9.6 | 10.3 | 10.5 | 10 | 9.4 | 8.3 | 7.4 | |
| 1965 | 6.9 | 7.1 | 7.2 | 8 | 8.8 | 9.8 | 10 | 10.2 | 10.3 | 9.7 | 9.2 | 8.5 | |
| 1966 | 7.7 | 7.6 | 7.7 | 8.5 | 9 | 9.1 | 99.9 | 10.7 | 10.1 | 9.5 | 8.7 | 8.6 | |
| 1967 | 7.9 | 7.7 | 7.6 | 8.1 | 8.9 | 9.6 | 10.3 | 10.5 | 10.5 | 9.7 | 9.1 | 8 | |
| 1968 | 7.3 | 7.3 | 8 | 8.3 | 8.7 | 9.5 | 10.2 | 10.2 | 10.4 | 9.3 | 8.8 | 7.8 | |
| 1969 | 6.5 | 6.3 | 7.2 | 8.1 | 9.1 | 10.2 | 10.4 | 10.5 | 9.8 | 9.2 | 8.7 | 8.1 | |
| 1970 | 7.5 | 7.7 | 7.9 | 8 | 8.7 | 9.6 | 10.2 | 10.2 | 10 | 9 | 8.3 | 7.5 | |
| 1971 | 7 | 6.9 | 6.7 | 7.5 | 8.5 | 9.1 | 10 | 10.6 | 10.4 | 9.3 | 8.3 | 7.3 | |
| 1972 | 6.4 | 6.2 | 6.9 | 7.6 | 8.8 | 9.5 | 10.5 | 10.6 | 10.2 | 9.1 | 8.4 | 7.3 | |
| 1973 | 7 | 7.2 | 7.9 | 8.4 | 8.6 | 9.2 | 10.1 | 10.3 | 10 | 9.2 | 8.2 | 8 | |
| 1974 | 7.2 | 7.2 | 7.3 | 8.1 | 8.5 | 9.7 | 10 | 10.9 | 10.6 | 9.7 | 8.6 | 8.2 | |
| 1975 | 7.3 | 6.8 | 7.2 | 7.7 | 8.7 | 9.4 | 10.2 | 10.4 | 10.4 | 9.6 | 9.2 | 7.8 | |
| 1976 | 7.2 | 7 | 7 | 7.8 | 8.7 | 9.3 | 10.1 | 10.1 | 10 | 9.4 | 8.6 | 8.1 | |
| 1977 | 7.6 | 7.9 | 8 | 8.3 | 8.8 | 9.7 | 9.9 | 10.8 | 10.3 | 9.2 | 8.6 | 7.9 | |
| 1978 | 7.6 | 7.9 | 8.3 | 8.9 | 9.4 | 10.3 | 10.4 | 10.9 | 10.5 | 9.8 | 8.2 | 7.3 | |
| 1979 | 6.5 | 6.9 | 7.5 | 8.3 | 9.5 | 10 | 10.8 | 10.7 | 10.5 | 9.8 | 9 | 8.6 | |
| 1980 | 7.7 | 7.6 | 7.9 | 8.6 | 9.5 | 9.5 | 10.6 | 10.9 | 10.5 | 9.9 | 9.2 | 8.6 | |
| 1981 | 8.3 | 8.3 | 8.8 | 9.2 | 9.4 | 9.9 | 10.3 | 10.5 | 10.2 | 9.7 | 9.3 | 8.5 | |
| 1982 | 7.2 | 7.5 | 8 | 8.8 | 9.9 | 10.7 | 11.4 | 11.8 | 11.4 | 10.3 | 8.8 | 8.3 | |
| 1983 | 8.6 | 8.6 | 9.3 | 10 | 10.6 | 11.3 | 11.7 | 12.4 | 11.4 | 10.3 | 9.5 | 7.7 | |
| 1984 | 7.5 | 7.8 | 8.4 | 9 | 9.7 | 10.3 | 11.4 | 11.6 | 10.6 | 9.7 | 8.5 | 6.9 | |
| 1985 | 6.8 | 6.8 | 7.2 | 8.2 | 9.6 | 10.6 | 11.5 | 11.6 | 10.8 | 9.6 | 6.8 | 6.4 | |
| 1986 | 7 | 6.6 | 8 | 8.4 | 9.4 | 11 | 10.9 | 11.8 | 10.8 | 9.8 | 8.4 | 7.8 | |
| 1987 | 7.6 | 7.9 | 8.3 | 8.9 | 9.8 | 10.6 | 11.1 | 11.5 | 11.1 | 10 | 9 | 8.2 | |
| 1988 | 7.4 | 7.5 | 7.5 | 8.6 | 9.6 | 10.4 | 11 | 11.4 | 10.6 | 9.6 | 8.7 | 7.9 | |
| 1989 | 7 | 5.8 | 6.8 | 8.2 | 9.5 | 10.7 | 11.3 | 11.2 | 11 | 9.9 | 8.9 | 8.2 | |
| 1990 | 8.1 | 7.7 | 8.2 | 9 | 9.9 | 10.8 | 11.8 | 12.1 | 12.1 | 10.7 | 9.9 | 8.2 | |
| 1991 | 7.1 | 7.7 | 7.9 | 8.4 | 9.7 | 9.7 | 10.8 | 11 | 11.2 | 10.1 | 8.9 | 8.3 | |
| 1992 | 7.9 | 8.1 | 9.5 | 9.5 | 10.2 | 10.7 | 11.1 | 11.4 | 11 | 10 | 9.1 | 7.8 | |
| 1993 | 6.7 | 6.7 | 7.6 | 8.6 | 9.7 | 10.8 | 11 | 11.2 | 11 | 10.1 | 8.5 | 7.9 | |
| 1994 | 8 | 7.4 | 8.6 | 9.3 | 10.1 | 10.6 | 11.6 | 11.5 | 11.3 | 10.7 | 9.3 | 8.4 | |
| 1995 | 8.2 | 8.6 | 8.8 | 9.2 | 10.2 | 11.2 | 11.8 | 11.5 | 11.3 | 10.2 | 9.4 | 8.9 | |
| 1996 | 8.2 | 7.8 | 8.4 | 9.2 | 10 | 10.4 | 11.5 | 11.5 | 10.5 | 9.9 | 8.7 | 7.6 | |
| 1997 | 7.7 | 7.9 | 8.1 | 9 | 10.3 | 10.9 | 11.7 | 12.2 | 11.6 | 11.3 | 9.9 | 9.3 | |
| 1998 | 8.7 | 9.2 | 9.7 | 9.9 | 10.4 | 11.4 | 11.7 | 12.3 | 12.1 | 10.7 | 9.8 | 9 | |
| 1999 | 8 | 7.8 | 8.1 | 8.9 | 9.5 | 10.4 | 11.1 | 11.5 | 11.9 | 10.1 | 9 | 8.5 | |
| 2000 | 7.5 | 7.7 | 8.1 | 9.1 | 10 | 11.1 | 11.3 | 11.7 | 11.4 | 10.3 | 9 | 8 | |
| 2001 | 7.9 | 7.7 | 8.1 | 8.7 | 9.7 | 10.6 | 11.3 | 11.4 | 11.4 | 10.2 | 9.2 | 8.3 | |
| 2002 | 8.1 | 7.9 | 7.7 | 8.7 | 9.4 | 10.5 | 11,2 | 11.7 | 11.3 | 10.0 | 9.0 | 8.8 | |
| 2003 | 8.8 | 8.5 | 8.7 | 9.2 | 9.9 | 10.9 | 11.3 | 11.4 | 11.4 | 10.9 | 9.0 | 8.5 | |
| 2004 | 7.8 | 7.9 | 8.3 | 9.1 | 10.4 | 11.0 | 11.8 | 11.9 | 11.2 | 10.6 | 9.4 | 8.6 | |
| 2005 | 7.7 | 8.0 | 8.8 | 9.4 | 10.7 | 11.2 | 11.6 | 12.1 | 11.5 | 10.4 | 9.5 | 8.3 | |
| 2006 | 8.61 | 8.49 | 8.41 | 8.75 | 10.08 | 10.86 | 11.66 | 12.09 | 11.49 | 10.55 | 9.29 | 8.5 | |
| 2007 | 7.8 | 7.9 | 7.9 | 9.0 | 10.0 | 10.2 | 11.2 | 11.6 | 11.0 | 10.0 | 9.0 | 8.0 | |
| 2008 | 7.46 | 7.33 | 7.68 | 8.06 | 9.36 | 9.77 | 10.84 | 11.30 | 11.16 | 10.14 | 9.39 | 7.87 | |
| 2009 | 7.29 | 7.20 | 7.5 | 8.4 | 9.54 | 10.4 | 11.4 | 11.74 | 11.8 | 10.5 | 9.0 | 7.0 | |
| 2010 | 8.11 | 8.68 | 9.12 | 8.96 | 9.54 | 10.36 | 11.16 | 11.93 | 11.08 | 10.37 | 8.98 | 8.5 | |
| 2011 | 7.77 | 7.49 | 7.77 | 8.53 | 9.32 | 10.35 | 10.76 | 11.38 | 11.17 | 10.14< | 8.66< | 8.01 | |
| 2012 | 7.29 | 7.35 | 7.63 | 8.73 | 9.82 | 9.76 | 10.37 | 10.98 | 10.92 | 9.66< | 8.85 | 8.32 | |
| 2013 | 7.64 | 7.44 | 7.48 | 8.27 | 9.05 | 9.72 | 10.96 | 10.76 | 10.65 | 10,10 | 8.69 | 7.68 | |
| 2014 | 7.63 | 7.25 | 7.90 | 8.80 | 9.72 | 10.30 | 10.79 | 11.36 | 11.20 | 10.72 | 10.14 | 9.03 | |
| 2015 | 8.75 | 9.00 | 8.96 | 9.40 | 9.88 | 11.17 | 11.97 | 12.23 | 11.30 | 10.55 | 9.61 | 9.01 | |
| 2016 | 8.45 | 8.77 | 9.05 | 9.71 | 10.21 | 11.16 | 11.90 | 12.52 | 11.27 | 10.40 | 10.42 | 8.63 | |
| 2018 | 8.06 | 7.71 | 8.00 | 8.81 | 10.31 | 10.63 | 11.40 | 11.50 | 11.11 | `0.27 | 9,54 | 8.72 | |
| 2019 | 8.45 | — | — | 8.96 | 10.05 | 10.87 | 10.98 | 11.26 | 10.85 | — | — | — | |
| 2020 | — | — | — | — | — | — | — | — | — | — | — | — | |
| 2021 | — | — | — | — | — | — | — | — | — | — | — | — | |
| 2022 | — | — | — | — | — | — | — | — | — | — | — | — | |
| Year/span> | Jan | Feb | Mar | Apr/span> | May | Jun/span> | Jul/span> | Aug/span> | Sep | Oct | Nov | Dec |