Year | Value | 2021 | 9.042 | 2020 | 9.026 | 2019 | 8.582 | 2018 | 8.85 | 2017 | 9.096 | 2016 | 9.345 | 2015 | 9.616 | 2014 | 9.965 | 2013 | 10.26 | 2012 | 10.557 | 2011 | 10.979 | 2010 | 11.214 | 2009 | 11.391 | 2008 | 11.508 | 2007 | 11.706 | 2006 | 11.887 | 2005 | 12.141 | 2004 | 12.356 | 2003 | 12.636 | 2002 | 12.989 | 2001 | 13.363 | 2000 | 13.738 | 1999 | 14.108 | 1998 | 14.432 | 1997 | 14.731 | 1996 | 15.044 | 1995 | 15.248 | 1994 | 15.478 | 1993 | 15.648 | 1992 | 15.873 | 1991 | 16.072 | 1990 | 16.246 | 1989 | 16.458 | 1988 | 16.633 | 1987 | 16.808 | 1986 | 16.949 | 1985 | 17.133 | 1984 | 17.367 | 1983 | 17.493 | 1982 | 17.791 | 1981 | 18.147 | 1980 | 18.545 | 1979 | 23.012 | 1978 | 23.44 | 1977 | 23.737 | 1976 | 35.86 | 1975 | 27.975 | 1974 | 24.196 | 1973 | 21.778 | 1972 | 21.972 | 1971 | 27.748 | 1970 | 34.376 | 1969 | 34.616 | 1968 | 21.771 | 1967 | 21.927 | 1966 | 22.142 | 1965 | 22.323 | 1964 | 22.591 | 1963 | 22.8 | 1962 | 23.088 | 1961 | 23.37 | 1960 | 23.669 |
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