| Year | Value | | 2024 | 80.342 | | 2023 | 79.855 | | 2022 | 80.719 | | 2021 | 79.004 | | 2020 | 79.887 | | 2019 | 80.89 | | 2018 | 80.634 | | 2017 | 80.252 | | 2016 | 79.858 | | 2015 | 79.74 | | 2014 | 79.582 | | 2013 | 79.365 | | 2012 | 78.813 | | 2011 | 78.121 | | 2010 | 78.212 | | 2009 | 77.997 | | 2008 | 77.702 | | 2007 | 77.468 | | 2006 | 77.158 | | 2005 | 76.909 | | 2004 | 76.591 | | 2003 | 76.319 | | 2002 | 76.011 | | 2001 | 75.689 | | 2000 | 75.365 | | 1999 | 74.051 | | 1998 | 74.67 | | 1997 | 74.303 | | 1996 | 73.933 | | 1995 | 73.522 | | 1994 | 73.134 | | 1993 | 72.739 | | 1992 | 72.332 | | 1991 | 71.963 | | 1990 | 71.519 | | 1989 | 71.081 | | 1988 | 70.618 | | 1987 | 70.047 | | 1986 | 69.561 | | 1985 | 69.051 | | 1984 | 68.53 | | 1983 | 67.904 | | 1982 | 67.328 | | 1981 | 66.85 | | 1980 | 66.441 | | 1979 | 65.944 | | 1978 | 65.42 | | 1977 | 64.546 | | 1976 | 63.631 |
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