Year | Value | 2021 | 11.116020588257 | 2020 | 11.745993174283 | 2019 | 12.874084003186 | 2018 | 13.307255324393 | 2017 | 14.377986248178 | 2016 | 15.070338750493 | 2015 | 14.486236739413 | 2014 | 15.585512978135 | 2013 | 15.251318764466 | 2012 | 16.181464823939 | 2011 | 15.547840534357 | 2010 | 14.822298121084 | 2009 | 14.894426071881 | 2008 | 15.065103945388 | 2007 | 15.038354700171 | 2006 | 15.024226686916 | 2005 | 15.233958672462 | 2004 | 15.225082141216 | 2003 | 15.314679144417 | 2002 | 15.652986721877 | 2001 | 16.085723101386 | 2000 | 16.555197101851 | 1999 | 17.039605091079 | 1998 | 17.813982983883 | 1997 | 18.499132137544 | 1996 | 18.915354115972 | 1995 | 19.176270645371 | 1994 | 19.665258988648 | 1993 | 20.019337043031 | 1992 | 20.354177201101 | 1991 | 21.4409105272 | 1990 | 22.424143576278 | 1989 | 23.013510082728 | 1988 | 23.761125678671 | 1987 | 24.575181829947 | 1986 | 24.29343268942 | 1985 | 23.704084314914 | 1984 | 23.362710281143 | 1983 | 23.728656877305 | 1982 | 24.966582983453 | 1981 | 24.317314623231 | 1980 | 22.993803998676 | 1979 | 22.90041102592 | 1978 | 23.311296918787 | 1977 | 23.795475309163 | 1976 | 24.481048174491 | 1975 | 26.347622045243 | 1974 | 27.50570610533 | 1973 | 29.399860844084 | 1972 | 30.548216577255 | 1971 | 31.159826576342 | 1970 | 32.799630527237 | 1969 | 33.30755450456 | 1968 | 34.270807541642 | 1967 | 33.594434698918 | 1966 | 34.481348080751 | 1965 | 36.303030777913 | 1964 | 37.310517421146 | 1963 | 39.953919399497 | 1962 | 36.780000703457 | 1961 | 26.595211439622 | 1960 | 28.164645275414 |
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