Year | Value | 2021 | 9.1092130742392 | 2020 | 9.103995302602 | 2019 | 9.3286021741009 | 2018 | 9.5261448377487 | 2017 | 9.7176679646503 | 2016 | 9.8412897325898 | 2015 | 9.7424763100215 | 2014 | 9.8584026212764 | 2013 | 9.7482316243389 | 2012 | 10.032726703204 | 2011 | 10.146493587102 | 2010 | 10.447993356573 | 2009 | 10.479543698163 | 2008 | 10.639153553578 | 2007 | 10.392534500621 | 2006 | 10.34410309092 | 2005 | 10.23009357046 | 2004 | 10.262209443888 | 2003 | 10.157251481096 | 2002 | 10.141029626498 | 2001 | 10.218538635213 | 2000 | 10.46050780847 | 1999 | 10.319788316011 | 1998 | 10.352302684436 | 1997 | 10.490366698974 | 1996 | 10.514249356008 | 1995 | 10.514340689035 | 1994 | 10.823217671367 | 1993 | 11.199599873781 | 1992 | 11.498747552787 | 1991 | 11.788349016396 | 1990 | 12.164444606484 | 1989 | 12.297010955576 | 1988 | 12.568040546307 | 1987 | 12.564755647463 | 1986 | 12.700869565495 | 1985 | 12.824968254791 | 1984 | 12.991007068688 | 1983 | 13.119678602989 | 1982 | 13.430533798038 | 1981 | 13.590965145612 | 1980 | 13.967632602226 | 1979 | 14.15520372408 | 1978 | 14.380688290848 | 1977 | 14.649931860943 | 1976 | 14.987601745434 | 1975 | 15.117985457694 | 1974 | 15.493725745215 | 1973 | 15.302860203969 | 1972 | 15.705909329406 | 1971 | 16.222841929412 | 1970 | 16.400462795754 | 1969 | 17.030565678358 | 1968 | 17.527232352917 | 1967 | 17.884076499919 | 1966 | 17.627046214275 | 1965 | 17.911266151301 | 1964 | 18.470128797217 | 1963 | 18.404679692235 | 1962 | 18.343899507715 | 1961 | 18.628864271812 | 1960 | 18.738289231975 |
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