| Year | Value | | 2024 | 71.280593277245 | | 2023 | 71.516259035502 | | 2022 | 71.847064172131 | | 2021 | 71.822306501427 | | 2020 | 72.109556477618 | | 2019 | 73.289193400812 | | 2018 | 74.306754234299 | | 2017 | 74.959665039722 | | 2016 | 75.380476515097 | | 2015 | 75.276085245929 | | 2014 | 74.628612951925 | | 2013 | 74.090210716009 | | 2012 | 74.281389133441 | | 2011 | 74.861536762473 | | 2010 | 75.459403040786 | | 2009 | 76.059897228965 | | 2008 | 76.182006506239 | | 2007 | 74.819108137962 | | 2006 | 71.499057904199 | | 2005 | 68.327299953478 | | 2004 | 68.089813831816 | | 2003 | 68.683814030687 | | 2002 | 68.564478596185 | | 2001 | 68.438544086735 | | 2000 | 68.300234577644 | | 1999 | 68.144489795918 | | 1998 | 67.965053286504 | | 1997 | 67.783528095317 | | 1996 | 67.764862887722 | | 1995 | 67.908680486695 | | 1994 | 68.063308373043 | | 1993 | 68.228272355039 | | 1992 | 68.405520612871 | | 1991 | 68.596378602271 | | 1990 | 68.801797462833 | | 1989 | 69.025831385309 | | 1988 | 69.270664899761 | | 1987 | 69.539503181312 | | 1986 | 69.784165136943 | | 1985 | 69.7827512707 | | 1984 | 69.561742909871 | | 1983 | 69.329317671037 | | 1982 | 69.072373425949 | | 1981 | 68.777593066986 | | 1980 | 68.433165526815 | | 1979 | 68.024896586384 | | 1978 | 67.542709681688 | | 1977 | 66.977237620071 | | 1976 | 66.315396721374 |
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