Year | Value | 2021 | 9.3516770238565 | 2020 | 9.1824223483994 | 2019 | 9.002520145425 | 2018 | 9.1224964064216 | 2017 | 9.2336992501369 | 2016 | 9.3674453973822 | 2015 | 9.4612417295453 | 2014 | 9.5719408740278 | 2013 | 9.6550588577153 | 2012 | 9.8195406295623 | 2011 | 9.9226154450441 | 2010 | 10.111234287418 | 2009 | 10.286905913568 | 2008 | 10.496953105257 | 2007 | 10.641416199809 | 2006 | 10.782789453525 | 2005 | 11.187438719527 | 2004 | 11.246908579274 | 2003 | 11.473536069535 | 2002 | 11.675178868172 | 2001 | 11.894180892288 | 2000 | 12.039161290484 | 1999 | 12.290446219293 | 1998 | 12.581968906513 | 1997 | 12.761053093981 | 1996 | 12.892055714134 | 1995 | 13.03677811495 | 1994 | 13.005854582442 | 1993 | 12.989290305769 | 1992 | 12.984199383723 | 1991 | 12.944742043031 | 1990 | 12.918162772829 | 1989 | 13.011896417133 | 1988 | 13.179004921187 | 1987 | 13.304258724929 | 1986 | 13.33797562226 | 1985 | 13.365376452522 | 1984 | 13.439650205796 | 1983 | 13.583145723501 | 1982 | 13.771002322012 | 1981 | 13.884268852604 | 1980 | 14.17963744289 | 1979 | 14.415867079881 | 1978 | 14.817283495074 | 1977 | 15.049464769184 | 1976 | 15.318805770888 | 1975 | 15.69354285121 | 1974 | 16.017654217675 | 1973 | 16.295207127085 | 1972 | 16.639213531626 | 1971 | 18.018055346073 | 1970 | 17.449068490151 | 1969 | 18.073968840024 | 1968 | 18.490389506305 | 1967 | 19.178451815873 | 1966 | 19.180572252107 | 1965 | 19.70340641563 | 1964 | 20.148596468856 | 1963 | 20.625241950426 | 1962 | 21.186429101023 | 1961 | 21.83790748499 | 1960 | 22.340744348997 |
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