| Year | Value | | 2024 | 77.999 | | 2023 | 77.811 | | 2022 | 76.966 | | 2021 | 73.352 | | 2020 | 74.109 | | 2019 | 77.422 | | 2018 | 77.13 | | 2017 | 76.972 | | 2016 | 76.962 | | 2015 | 76.929 | | 2014 | 76.886 | | 2013 | 76.819 | | 2012 | 76.727 | | 2011 | 76.524 | | 2010 | 76.293 | | 2009 | 76.135 | | 2008 | 76.119 | | 2007 | 76.144 | | 2006 | 76.025 | | 2005 | 75.877 | | 2004 | 75.664 | | 2003 | 75.548 | | 2002 | 75.382 | | 2001 | 75.24 | | 2000 | 74.972 | | 1999 | 74.708 | | 1998 | 74.358 | | 1997 | 74.085 | | 1996 | 73.742 | | 1995 | 73.468 | | 1994 | 73.152 | | 1993 | 72.905 | | 1992 | 72.642 | | 1991 | 72.373 | | 1990 | 72.025 | | 1989 | 71.64 | | 1988 | 71.329 | | 1987 | 70.962 | | 1986 | 70.441 | | 1985 | 69.898 | | 1984 | 69.392 | | 1983 | 69.035 | | 1982 | 68.622 | | 1981 | 68.127 | | 1980 | 67.622 | | 1979 | 67.068 | | 1978 | 66.478 | | 1977 | 65.865 | | 1976 | 65.193 |
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