Year | Value | 2021 | 12.115 | 2020 | 12.16 | 2019 | 11.485 | 2018 | 10.816 | 2017 | 11.789 | 2016 | 11.659 | 2015 | 12.591 | 2014 | 12.325 | 2013 | 12.469 | 2012 | 13.497 | 2011 | 14.313 | 2010 | 14.715 | 2009 | 16.632 | 2008 | 17.039 | 2007 | 15.637 | 2006 | 15.511 | 2005 | 15.668 | 2004 | 16.013 | 2003 | 16.521 | 2002 | 17.202 | 2001 | 18.091 | 2000 | 19.829 | 1999 | 17.829 | 1998 | 18.474 | 1997 | 20.118 | 1996 | 20.823 | 1995 | 19.847 | 1994 | 18.99 | 1993 | 18.597 | 1992 | 19.228 | 1991 | 18.504 | 1990 | 20.916 | 1989 | 20.97 | 1988 | 20.798 | 1987 | 20.555 | 1986 | 20.508 | 1985 | 21.859 | 1984 | 20.789 | 1983 | 21.392 | 1982 | 20.949 | 1981 | 21.349 | 1980 | 22.367 | 1979 | 24.564 | 1978 | 23.135 | 1977 | 23.997 | 1976 | 23.142 | 1975 | 22.349 | 1974 | 22.902 | 1973 | 23.706 | 1972 | 24.297 | 1971 | 25.084 | 1970 | 25.854 | 1969 | 27.275 | 1968 | 28.753 | 1967 | 30.207 | 1966 | 31.681 | 1965 | 32.881 | 1964 | 33.998 | 1963 | 34.447 | 1962 | 34.578 | 1961 | 34.715 | 1960 | 34.85 |
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