Year | Value | 2021 | 11.596 | 2020 | 11.39 | 2019 | 11.041 | 2018 | 11.444 | 2017 | 11.891 | 2016 | 12.275 | 2015 | 12.447 | 2014 | 12.81 | 2013 | 13.129 | 2012 | 13.568 | 2011 | 14.856 | 2010 | 15.358 | 2009 | 14.591 | 2008 | 15.096 | 2007 | 15.542 | 2006 | 15.566 | 2005 | 15.593 | 2004 | 15.711 | 2003 | 15.712 | 2002 | 15.684 | 2001 | 15.702 | 2000 | 15.778 | 1999 | 15.878 | 1998 | 15.806 | 1997 | 16.136 | 1996 | 15.885 | 1995 | 15.753 | 1994 | 15.868 | 1993 | 15.492 | 1992 | 38.55 | 1991 | 40.463 | 1990 | 18.009 | 1989 | 18.337 | 1988 | 20.457 | 1987 | 17.304 | 1986 | 17.646 | 1985 | 17.707 | 1984 | 17.586 | 1983 | 17.777 | 1982 | 17.994 | 1981 | 18.068 | 1980 | 18.142 | 1979 | 18.228 | 1978 | 18.392 | 1977 | 18.345 | 1976 | 20.137 | 1975 | 20.436 | 1974 | 20.748 | 1973 | 18.912 | 1972 | 19.046 | 1971 | 19.185 | 1970 | 19.325 | 1969 | 19.471 | 1968 | 19.628 | 1967 | 19.794 | 1966 | 19.969 | 1965 | 20.153 | 1964 | 20.361 | 1963 | 20.539 | 1962 | 20.739 | 1961 | 21.018 | 1960 | 21.131 |
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