| Year | Value | | 2024 | 82.839 | | 2023 | 82.408 | | 2022 | 81.956 | | 2021 | 81.483 | | 2020 | 80.988 | | 2019 | 80.47 | | 2018 | 79.93 | | 2017 | 79.365 | | 2016 | 78.775 | | 2015 | 78.159 | | 2014 | 77.517 | | 2013 | 76.862 | | 2012 | 76.194 | | 2011 | 75.511 | | 2010 | 74.817 | | 2009 | 74.109 | | 2008 | 73.389 | | 2007 | 72.655 | | 2006 | 71.91 | | 2005 | 71.152 | | 2004 | 70.383 | | 2003 | 69.6 | | 2002 | 69.847 | | 2001 | 70.093 | | 2000 | 70.338 | | 1999 | 70.582 | | 1998 | 70.825 | | 1997 | 71.066 | | 1996 | 71.306 | | 1995 | 71.431 | | 1994 | 71.069 | | 1993 | 70.704 | | 1992 | 70.337 | | 1991 | 69.966 | | 1990 | 69.593 | | 1989 | 69.24 | | 1988 | 68.892 | | 1987 | 68.541 | | 1986 | 68.188 | | 1985 | 67.38 | | 1984 | 66.409 | | 1983 | 65.421 | | 1982 | 64.422 | | 1981 | 63.409 | | 1980 | 62.542 | | 1979 | 62.263 | | 1978 | 61.983 | | 1977 | 61.702 | | 1976 | 61.421 | | 1975 | 61.138 |
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