Year | Value | 2022 | 12.804 | 2021 | 12.831 | 2020 | 12.847 | 2019 | 12.853 | 2018 | 12.847 | 2017 | 12.83 | 2016 | 12.802 | 2015 | 12.762 | 2014 | 12.712 | 2013 | 12.652 | 2012 | 12.58 | 2011 | 12.498 | 2010 | 12.406 | 2009 | 12.303 | 2008 | 12.201 | 2007 | 12.1 | 2006 | 12 | 2005 | 11.9 | 2004 | 11.802 | 2003 | 11.703 | 2002 | 11.606 | 2001 | 11.509 | 2000 | 11.413 | 1999 | 11.869 | 1998 | 12.533 | 1997 | 13.229 | 1996 | 13.957 | 1995 | 14.72 | 1994 | 15.515 | 1993 | 16.346 | 1992 | 17.211 | 1991 | 18.114 | 1990 | 19.052 | 1989 | 19.737 | 1988 | 20.341 | 1987 | 20.96 | 1986 | 21.592 | 1985 | 22.238 | 1984 | 22.897 | 1983 | 23.571 | 1982 | 24.257 | 1981 | 24.957 | 1980 | 25.67 | 1979 | 26.129 | 1978 | 26.503 | 1977 | 26.88 | 1976 | 27.261 | 1975 | 27.646 | 1974 | 28.033 | 1973 | 28.424 | 1972 | 28.818 | 1971 | 29.216 | 1970 | 29.616 | 1969 | 30.02 | 1968 | 30.426 | 1967 | 30.837 | 1966 | 31.25 | 1965 | 31.666 | 1964 | 32.084 | 1963 | 32.507 | 1962 | 32.932 | 1961 | 33.359 | 1960 | 33.789 |
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