Year | Value | 2021 | 8.6511655564307 | 2020 | 7.477364554491 | 2019 | 7.0391327049649 | 2018 | 7.0370626155739 | 2017 | 7.052696892125 | 2016 | 7.1122379294868 | 2015 | 7.2030617323952 | 2014 | 7.2981291365475 | 2013 | 7.4246246658838 | 2012 | 7.5429778585073 | 2011 | 7.668885050832 | 2010 | 7.8333157700516 | 2009 | 7.9373937977756 | 2008 | 8.1040916991847 | 2007 | 8.1377609957164 | 2006 | 8.2203272436757 | 2005 | 8.3801734507662 | 2004 | 8.508015930041 | 2003 | 8.6495806410541 | 2002 | 8.7889595207021 | 2001 | 8.949627110031 | 2000 | 9.0808071528127 | 1999 | 9.1927675181847 | 1998 | 9.4022932649184 | 1997 | 9.5986348473598 | 1996 | 9.7982809937552 | 1995 | 9.9597373069488 | 1994 | 10.110047994959 | 1993 | 10.256519400948 | 1992 | 10.391434880805 | 1991 | 10.618376959571 | 1990 | 10.746273207228 | 1989 | 10.943237146583 | 1988 | 11.202321764932 | 1987 | 11.440628717803 | 1986 | 11.674502039948 | 1985 | 11.957204917873 | 1984 | 12.220283989155 | 1983 | 12.505136930583 | 1982 | 12.801595885589 | 1981 | 13.068551899699 | 1980 | 13.327353648085 | 1979 | 13.597977977198 | 1978 | 13.930052326367 | 1977 | 14.246816800822 | 1976 | 14.863844739871 | 1975 | 15.188481747727 | 1974 | 15.342894122723 | 1973 | 15.648349308922 | 1972 | 16.041227244622 | 1971 | 17.750904968161 | 1970 | 16.821596105227 | 1969 | 16.797156010767 | 1968 | 17.084185030505 | 1967 | 17.80846928561 | 1966 | 18.018421121853 | 1965 | 18.383300757442 | 1964 | 18.052231284721 | 1963 | 18.378392520845 | 1962 | 18.687705352942 | 1961 | 18.985836048008 | 1960 | 19.306479674923 |
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