| Year | Value | | 2024 | 83.479 | | 2023 | 83.368 | | 2022 | 82.804 | | 2021 | 82.184 | | 2020 | 82.165 | | 2019 | 84.064 | | 2018 | 83.8 | | 2017 | 83.51 | | 2016 | 83.19 | | 2015 | 82.837 | | 2014 | 82.448 | | 2013 | 82.019 | | 2012 | 81.552 | | 2011 | 81.054 | | 2010 | 80.533 | | 2009 | 79.999 | | 2008 | 79.461 | | 2007 | 78.928 | | 2006 | 78.41 | | 2005 | 77.918 | | 2004 | 77.46 | | 2003 | 77.047 | | 2002 | 76.689 | | 2001 | 76.388 | | 2000 | 76.133 | | 1999 | 75.915 | | 1998 | 75.725 | | 1997 | 75.553 | | 1996 | 75.388 | | 1995 | 75.227 | | 1994 | 75.065 | | 1993 | 74.897 | | 1992 | 74.72 | | 1991 | 74.532 | | 1990 | 74.334 | | 1989 | 74.125 | | 1988 | 73.909 | | 1987 | 73.685 | | 1986 | 73.455 | | 1985 | 73.217 | | 1984 | 72.969 | | 1983 | 72.709 | | 1982 | 72.431 | | 1981 | 72.132 | | 1980 | 71.775 | | 1979 | 71.425 | | 1978 | 71.045 | | 1977 | 70.633 | | 1976 | 70.184 |
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