Year | Value | 2021 | 11.356 | 2020 | 9.603 | 2019 | 8.923 | 2018 | 9.324 | 2017 | 9.936 | 2016 | 10.45 | 2015 | 11.202 | 2014 | 12.193 | 2013 | 13.019 | 2012 | 13.946 | 2011 | 14.926 | 2010 | 15.911 | 2009 | 17.283 | 2008 | 17.525 | 2007 | 17.861 | 2006 | 18.174 | 2005 | 18.845 | 2004 | 18.372 | 2003 | 17.578 | 2002 | 16.588 | 2001 | 15.449 | 2000 | 14.521 | 1999 | 13.519 | 1998 | 12.515 | 1997 | 11.576 | 1996 | 10.703 | 1995 | 9.699 | 1994 | 8.824 | 1993 | 8.036 | 1992 | 7.5 | 1991 | 7.197 | 1990 | 7.155 | 1989 | 7.304 | 1988 | 7.544 | 1987 | 7.939 | 1986 | 8.349 | 1985 | 8.802 | 1984 | 9.317 | 1983 | 10.494 | 1982 | 10.081 | 1981 | 10.509 | 1980 | 10.91 | 1979 | 11.327 | 1978 | 11.84 | 1977 | 12.395 | 1976 | 12.967 | 1975 | 13.483 | 1974 | 13.94 | 1973 | 14.323 | 1972 | 14.761 | 1971 | 15.107 | 1970 | 15.415 | 1969 | 15.705 | 1968 | 16.033 | 1967 | 16.411 | 1966 | 16.825 | 1965 | 17.267 | 1964 | 17.679 | 1963 | 18.046 | 1962 | 18.24 | 1961 | 18.564 | 1960 | 18.871 |
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