| Year | Value | | 2023 | 77.587804878049 | | 2022 | 76.187804878049 | | 2021 | 73.824390243902 | | 2020 | 75.931707317073 | | 2019 | 76.682926829268 | | 2018 | 77.885365853658 | | 2017 | 76.685365853658 | | 2016 | 76.541463414634 | | 2015 | 76.60243902439 | | 2014 | 76.339024390244 | | 2013 | 76.490243902439 | | 2012 | 76.3 | | 2011 | 76.082926829268 | | 2010 | 75.990243902439 | | 2009 | 75.143902439024 | | 2008 | 75.136585365854 | | 2007 | 74.339024390244 | | 2006 | 73.839024390244 | | 2005 | 73.982926829268 | | 2004 | 74.205609756098 | | 2003 | 74.055731707317 | | 2002 | 73.965219512195 | | 2001 | 73.580195121951 | | 2000 | 73.396804878049 | | 1999 | 73.14387804878 | | 1998 | 73.287780487805 | | 1997 | 73.342975609756 | | 1996 | 73.444731707317 | | 1995 | 73.564926829268 | | 1994 | 73.587780487805 | | 1993 | 73.693878048781 | | 1992 | 73.621658536585 | | 1991 | 73.766731707317 | | 1990 | 73.696341463415 | | 1989 | 73.620487804878 | | 1988 | 73.21312195122 | | 1987 | 72.983341463415 | | 1986 | 72.588463414634 | | 1985 | 72.238609756098 | | 1984 | 72.098048780488 | | 1983 | 72.106780487805 | | 1982 | 72.101487804878 | | 1981 | 71.919292682927 | | 1980 | 72.032585365854 | | 1979 | 71.280463414634 | | 1978 | 71.710219512195 | | 1977 | 71.61512195122 | | 1976 | 71.846195121951 | | 1975 | 71.709414634146 |
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