| Year | Value | | 2022 | 82.853836730948 | | 2021 | 82.223600847431 | | 2020 | 81.818220699828 | | 2019 | 83.016901671993 | | 2018 | 83.200979043852 | | 2017 | 82.857762996271 | | 2016 | 83.96099706524 | | 2015 | 83.642263746895 | | 2014 | 84.224655492523 | | 2013 | 84.860059246834 | | 2012 | 84.928649162784 | | 2011 | 84.860669196855 | | 2010 | 85.38307410449 | | 2009 | 86.275392206363 | | 2008 | 84.092432228916 | | 2007 | 83.296269608976 | | 2006 | 83.506132314519 | | 2005 | 84.14261600902 | | 2004 | 84.532868806785 | | 2003 | 84.187822946849 | | 2002 | 84.006315052638 | | 2001 | 83.42996243898 | | 2000 | 82.78340625318 | | 1999 | 82.950746131313 | | 1998 | 82.218946200354 | | 1997 | 81.69885830261 | | 1996 | 80.644466495896 | | 1995 | 80.748140800263 | | 1994 | 87.955862216115 | | 1993 | 88.370645185903 | | 1992 | 88.200650430695 | | 1991 | 86.638329943238 | | 1990 | 85.074656838939 | | 1989 | 84.405794758099 | | 1988 | 85.45309720504 | | 1987 | 85.839985963835 | | 1986 | 87.229496650102 | | 1985 | 85.296550041836 | | 1984 | 86.365566687611 | | 1983 | 86.577445580664 | | 1982 | 86.691921007822 | | 1981 | 86.799347418102 | | 1980 | 85.97008025603 | | 1979 | 85.050551634643 | | 1978 | 85.330188453041 | | 1977 | 86.399188415022 | | 1976 | 89.211445345693 | | 1975 | 90.687124110035 | | 1974 | 88.684918861912 | | 1973 | 84.748996106573 | | 1972 | 85.521634290416 | | 1971 | 84.311217548472 | | 1970 | 83.73948136857 |
|