Year | Value | 2021 | 9.7 | 2020 | 9.537 | 2019 | 9.38 | 2018 | 9.573 | 2017 | 9.865 | 2016 | 10.077 | 2015 | 10.396 | 2014 | 10.551 | 2013 | 10.857 | 2012 | 11.166 | 2011 | 11.301 | 2010 | 11.653 | 2009 | 11.98 | 2008 | 12.275 | 2007 | 12.529 | 2006 | 12.777 | 2005 | 13.136 | 2004 | 13.465 | 2003 | 13.854 | 2002 | 14.186 | 2001 | 14.384 | 2000 | 14.637 | 1999 | 15.636 | 1998 | 15.876 | 1997 | 15.676 | 1996 | 16.403 | 1995 | 15.689 | 1994 | 15.967 | 1993 | 16.177 | 1992 | 16.391 | 1991 | 16.591 | 1990 | 16.833 | 1989 | 17.142 | 1988 | 17.429 | 1987 | 17.727 | 1986 | 17.994 | 1985 | 18.164 | 1984 | 18.274 | 1983 | 18.455 | 1982 | 18.648 | 1981 | 18.814 | 1980 | 19.005 | 1979 | 19.206 | 1978 | 19.722 | 1977 | 19.629 | 1976 | 19.769 | 1975 | 19.962 | 1974 | 20.068 | 1973 | 20.354 | 1972 | 20.532 | 1971 | 20.777 | 1970 | 21.094 | 1969 | 21.373 | 1968 | 21.616 | 1967 | 21.937 | 1966 | 22.149 | 1965 | 23.213 | 1964 | 23.756 | 1963 | 23.328 | 1962 | 23.547 | 1961 | 23.642 | 1960 | 23.167 |
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