| Year | Value | | 2024 | 82.522 | | 2023 | 82.368 | | 2022 | 81.857 | | 2021 | 81.083 | | 2020 | 80.409 | | 2019 | 82.945 | | 2018 | 82.714 | | 2017 | 82.458 | | 2016 | 82.147 | | 2015 | 81.785 | | 2014 | 81.395 | | 2013 | 80.974 | | 2012 | 80.499 | | 2011 | 79.994 | | 2010 | 79.444 | | 2009 | 78.837 | | 2008 | 78.262 | | 2007 | 77.741 | | 2006 | 77.323 | | 2005 | 76.909 | | 2004 | 76.484 | | 2003 | 76.097 | | 2002 | 75.766 | | 2001 | 75.486 | | 2000 | 75.25 | | 1999 | 75.048 | | 1998 | 74.872 | | 1997 | 74.713 | | 1996 | 74.558 | | 1995 | 74.404 | | 1994 | 74.245 | | 1993 | 74.071 | | 1992 | 73.876 | | 1991 | 73.654 | | 1990 | 73.405 | | 1989 | 73.131 | | 1988 | 72.836 | | 1987 | 72.52 | | 1986 | 72.184 | | 1985 | 71.831 | | 1984 | 71.465 | | 1983 | 71.089 | | 1982 | 70.704 | | 1981 | 70.313 | | 1980 | 69.915 | | 1979 | 69.507 | | 1978 | 69.083 | | 1977 | 68.639 | | 1976 | 68.172 |
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