Year | Value | 2022 | 31.877 | 2021 | 31.24 | 2020 | 30.607 | 2019 | 29.98 | 2018 | 29.358 | 2017 | 28.743 | 2016 | 28.134 | 2015 | 27.53 | 2014 | 26.934 | 2013 | 26.346 | 2012 | 25.767 | 2011 | 25.196 | 2010 | 24.633 | 2009 | 24.079 | 2008 | 23.534 | 2007 | 22.996 | 2006 | 22.339 | 2005 | 21.537 | 2004 | 20.757 | 2003 | 19.996 | 2002 | 19.258 | 2001 | 18.54 | 2000 | 17.844 | 1999 | 17.166 | 1998 | 16.51 | 1997 | 15.875 | 1996 | 15.407 | 1995 | 15.131 | 1994 | 14.86 | 1993 | 14.593 | 1992 | 14.33 | 1991 | 14.07 | 1990 | 13.815 | 1989 | 13.563 | 1988 | 13.316 | 1987 | 13.072 | 1986 | 12.832 | 1985 | 12.334 | 1984 | 11.544 | 1983 | 10.796 | 1982 | 10.091 | 1981 | 9.428 | 1980 | 8.805 | 1979 | 8.218 | 1978 | 7.668 | 1977 | 7.151 | 1976 | 6.668 | 1975 | 6.347 | 1974 | 6.222 | 1973 | 6.1 | 1972 | 5.98 | 1971 | 5.861 | 1970 | 5.746 | 1969 | 5.632 | 1968 | 5.52 | 1967 | 5.411 | 1966 | 5.303 | 1965 | 5.198 | 1964 | 5.095 | 1963 | 4.993 | 1962 | 4.893 | 1961 | 4.796 | 1960 | 4.7 |
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