Year | Value | 2021 | 71.86924485442 | 2020 | 72.696081876477 | 2019 | 74.337935843546 | 2018 | 74.042478718196 | 2017 | 73.876536343496 | 2016 | 73.445304198417 | 2015 | 73.128817634898 | 2014 | 72.910683517788 | 2013 | 72.696119352971 | 2012 | 72.260905633236 | 2011 | 71.88726030188 | 2010 | 71.41737229763 | 2009 | 71.102927896891 | 2008 | 70.557652488079 | 2007 | 70.255157670408 | 2006 | 69.789095407033 | 2005 | 69.201859441643 | 2004 | 69.112331849457 | 2003 | 68.77342079246 | 2002 | 68.650378485346 | 2001 | 68.555882691225 | 2000 | 68.379542167384 | 1999 | 68.187433467839 | 1998 | 68.506024211 | 1997 | 68.083133799086 | 1996 | 67.594982181295 | 1995 | 67.030136231824 | 1994 | 66.974420240759 | 1993 | 66.97582932289 | 1992 | 67.7695205899 | 1991 | 68.644698852462 | 1990 | 68.920283281013 | 1989 | 69.01865201681 | 1988 | 68.928705167559 | 1987 | 68.900673506976 | 1986 | 68.752464452482 | 1985 | 67.861398045305 | 1984 | 67.507380296902 | 1983 | 67.619639827168 | 1982 | 67.578038026333 | 1981 | 67.247540196357 | 1980 | 66.933156676132 | 1979 | 66.799235250655 | 1978 | 66.842912511141 | 1977 | 66.777437471658 | 1976 | 66.782312527015 | 1975 | 66.775703412852 | 1974 | 66.965126524868 | 1973 | 66.80707243211 | 1972 | 66.670540710249 | 1971 | 66.499194192487 | 1970 | 66.252517093097 | 1969 | 65.650838093946 | 1968 | 65.98963385233 | 1967 | 65.86509314234 | 1966 | 66.070391419777 | 1965 | 65.90015588587 | 1964 | 65.966296591066 | 1963 | 65.483301939591 | 1962 | 64.916196722774 | 1961 | 65.076215767069 | 1960 | 64.850632914706 |
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