Year | Value | 2021 | 74.932076972292 | 2020 | 76.087716844628 | 2019 | 77.266844666145 | 2018 | 76.97682268184 | 2017 | 76.947442639573 | 2016 | 76.969811417191 | 2015 | 76.571877764779 | 2014 | 76.675623611305 | 2013 | 76.355162986981 | 2012 | 75.993488603453 | 2011 | 75.888474883428 | 2010 | 75.293965778631 | 2009 | 74.930363926658 | 2008 | 74.575952678078 | 2007 | 74.250648721077 | 2006 | 74.09260273081 | 2005 | 73.844995135921 | 2004 | 73.730434932738 | 2003 | 73.382252782526 | 2002 | 73.242415488092 | 2001 | 73.096148193734 | 2000 | 72.719724722779 | 1999 | 72.184561074087 | 1998 | 71.898237675996 | 1997 | 71.517258069682 | 1996 | 71.336058018995 | 1995 | 71.025421428289 | 1994 | 70.869543944747 | 1993 | 70.845986615145 | 1992 | 70.732837131416 | 1991 | 70.575221303477 | 1990 | 70.656331337259 | 1989 | 70.731972259749 | 1988 | 70.861708225052 | 1987 | 70.611763331234 | 1986 | 70.565136039744 | 1985 | 70.312883466324 | 1984 | 70.349114856134 | 1983 | 70.38978516943 | 1982 | 70.455473318732 | 1981 | 70.372050177777 | 1980 | 69.888984623612 | 1979 | 70.247761092643 | 1978 | 70.144665762258 | 1977 | 70.245973064407 | 1976 | 70.320589866464 | 1975 | 70.175972670731 | 1974 | 70.352086320652 | 1973 | 70.100277452269 | 1972 | 69.96063415784 | 1971 | 69.501481137198 | 1970 | 69.330415208253 | 1969 | 69.054739257532 | 1968 | 69.555109561735 | 1967 | 69.324274475517 | 1966 | 69.823455367313 | 1965 | 69.323459590743 | 1964 | 69.170226989656 | 1963 | 68.674002628238 | 1962 | 67.690161983511 | 1961 | 68.235932234944 | 1960 | 67.933951962905 |
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