Year | Value | 2021 | 42.426813746288 | 2020 | 41.726771319474 | 2019 | 41.132795927026 | 2018 | 40.549427238014 | 2017 | 39.955451845566 | 2016 | 39.372083156555 | 2015 | 38.778107764107 | 2014 | 38.194739075095 | 2013 | 37.600763682647 | 2012 | 37.123462028002 | 2011 | 37.123462028002 | 2010 | 37.123462028002 | 2009 | 37.123462028002 | 2008 | 36.593126856173 | 2007 | 35.002121340687 | 2006 | 35.002121340687 | 2005 | 33.94145099703 | 2004 | 31.820110309716 | 2003 | 31.820110309716 | 2002 | 30.22910479423 | 2001 | 30.22910479423 | 2000 | 29.168434450573 | 1999 | 28.638099278744 | 1998 | 27.577428935087 | 1997 | 25.986423419601 | 1996 | 25.456088247773 | 1995 | 24.395417904115 | 1994 | 22.274077216801 | 1993 | 24.395417904115 | 1992 | 24.395417904115 | 1991 | 24.925753075944 | 1990 | 23.865082732287 | 1989 | 23.334747560458 | 1988 | 22.80441238863 | 1987 | 22.80441238863 | 1986 | 22.80441238863 | 1985 | 21.743742044972 | 1984 | 21.743742044972 | 1983 | 21.213406873144 | 1982 | 22.274077216801 | 1981 | 21.213406873144 | 1980 | 20.152736529487 | 1979 | 21.743742044972 | 1978 | 21.743742044972 | 1977 | 21.213406873144 | 1976 | 21.213406873144 | 1975 | 21.213406873144 | 1974 | 21.743742044972 | 1973 | 21.743742044972 | 1972 | 21.213406873144 | 1971 | 20.683071701315 | 1970 | 19.092066185829 | 1969 | 19.622401357658 | 1968 | 19.092066185829 | 1967 | 18.031395842172 | 1966 | 18.561731014001 | 1965 | 18.031395842172 | 1964 | 15.910055154858 | 1963 | 15.379719983029 | 1962 | 14.849384811201 | 1961 | 13.788714467543 |
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