Year | Value | 2022 | 42.368296693702 | 2021 | 41.830052868299 | 2020 | 41.294416123698 | 2019 | 40.759282863714 | 2018 | 40.224545326342 | 2017 | 39.687196500395 | 2016 | 39.160903764528 | 2015 | 38.631319192145 | 2014 | 38.089067587354 | 2013 | 37.561873234206 | 2012 | 37.048531690271 | 2011 | 36.53701418725 | 2010 | 36.015180198568 | 2009 | 35.499628613874 | 2008 | 34.991709774051 | 2007 | 34.488606237255 | 2006 | 34.073159993089 | 2005 | 33.615688865608 | 2004 | 33.15567697794 | 2003 | 32.711659399915 | 2002 | 32.272659280001 | 2001 | 31.835831023986 | 2000 | 31.40950851282 | 1999 | 31.047552039911 | 1998 | 30.685205095289 | 1997 | 30.320545915161 | 1996 | 29.965784363439 | 1995 | 29.629352891812 | 1994 | 29.236112767013 | 1993 | 28.809782893738 | 1992 | 28.379386946067 | 1991 | 27.949982171595 | 1990 | 27.510868504833 | 1989 | 26.960250196668 | 1988 | 26.399585348314 | 1987 | 25.831558160145 | 1986 | 25.262460615183 | 1985 | 24.694417481598 | 1984 | 24.152482625362 | 1983 | 23.655545853447 | 1982 | 23.207921164414 | 1981 | 22.798769778722 | 1980 | 22.381724719096 | 1979 | 21.995194430312 | 1978 | 21.60087891261 | 1977 | 21.161390713797 | 1976 | 20.732412488322 | 1975 | 20.296389923251 | 1974 | 19.867207881236 | 1973 | 19.445423004575 | 1972 | 19.013252236895 | 1971 | 18.583036815669 | 1970 | 18.17200150868 | 1969 | 17.792961479603 | 1968 | 17.403275964362 | 1967 | 17.024101217401 | 1966 | 16.653910912248 | 1965 | 16.292792453343 | 1964 | 15.930408165577 | 1963 | 15.580253674147 | 1962 | 15.245118184167 | 1961 | 14.929962953936 | 1960 | 14.624216817724 |
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