Year | Value | 2021 | 6.028 | 2020 | 5.692 | 2019 | 5.162 | 2018 | 5.275 | 2017 | 4.868 | 2016 | 5.198 | 2015 | 5.695 | 2014 | 5.401 | 2013 | 5.472 | 2012 | 5.808 | 2011 | 5.938 | 2010 | 6.409 | 2009 | 6.205 | 2008 | 6.15 | 2007 | 5.636 | 2006 | 5.601 | 2005 | 5.151 | 2004 | 5.175 | 2003 | 5.19 | 2002 | 5.291 | 2001 | 5.446 | 2000 | 5.844 | 1999 | 6.321 | 1998 | 6.624 | 1997 | 6.97 | 1996 | 7.347 | 1995 | 8.178 | 1994 | 7.807 | 1993 | 7.887 | 1992 | 7.977 | 1991 | 8.137 | 1990 | 8.315 | 1989 | 8.642 | 1988 | 8.868 | 1987 | 9.229 | 1986 | 9.597 | 1985 | 9.919 | 1984 | 10.207 | 1983 | 10.194 | 1982 | 10.185 | 1981 | 10.186 | 1980 | 10.24 | 1979 | 10.424 | 1978 | 10.71 | 1977 | 11.086 | 1976 | 11.576 | 1975 | 11.983 | 1974 | 12.541 | 1973 | 12.983 | 1972 | 13.34 | 1971 | 13.595 | 1970 | 13.913 | 1969 | 14.332 | 1968 | 14.744 | 1967 | 15.114 | 1966 | 15.446 | 1965 | 15.917 | 1964 | 16.357 | 1963 | 16.815 | 1962 | 17.338 | 1961 | 17.847 | 1960 | 18.469 |
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