| Year | Value | | 2022 | 81.755964330746 | | 2021 | 82.195019375991 | | 2020 | 83.027294704485 | | 2019 | 81.055311958104 | | 2018 | 81.24685124274 | | 2017 | 81.763882731476 | | 2016 | 83.020057862571 | | 2015 | 83.405341508687 | | 2014 | 84.53375374698 | | 2013 | 84.26930548974 | | 2012 | 84.792861658764 | | 2011 | 85.592077978799 | | 2010 | 86.51867658789 | | 2009 | 86.062700612258 | | 2008 | 85.974091602743 | | 2007 | 84.457862199742 | | 2006 | 84.90657090592 | | 2005 | 85.417555540396 | | 2004 | 84.046166715407 | | 2003 | 83.2898583342 | | 2002 | 82.257205454459 | | 2001 | 82.059811168932 | | 2000 | 82.267118002184 | | 1999 | 81.322559606526 | | 1998 | 80.850882291576 | | 1997 | 81.472317859619 | | 1996 | 82.704523763675 | | 1995 | 82.18163077719 | | 1994 | 84.071198978898 | | 1993 | 84.998891576324 | | 1992 | 82.612161490203 | | 1991 | 81.621334753938 | | 1990 | 78.936526057919 | | 1989 | 77.492885149588 | | 1988 | 77.547799377547 | | 1987 | 77.191199682487 | | 1986 | 78.129217968656 | | 1985 | 81.067000495754 | | 1984 | 83.335830505663 | | 1983 | 82.200892322412 | | 1982 | 82.088886707287 | | 1981 | 82.348571216695 | | 1980 | 79.705368504848 | | 1979 | 78.994847265258 | | 1978 | 79.531299013205 | | 1977 | 83.492812386615 | | 1976 | 86.192608353491 | | 1975 | 89.420346843304 | | 1974 | 84.24293092725 | | 1973 | 75.380910891776 | | 1972 | 75.237788698664 | | 1971 | 79.393438077705 | | 1970 | 77.385202469036 |
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