Year | Value | 2021 | 8.922 | 2020 | 9.344 | 2019 | 9.752 | 2018 | 10.348 | 2017 | 10.182 | 2016 | 10.351 | 2015 | 10.972 | 2014 | 10.86 | 2013 | 11.122 | 2012 | 11.191 | 2011 | 11.76 | 2010 | 11.417 | 2009 | 11.487 | 2008 | 10.83 | 2007 | 9.921 | 2006 | 9.752 | 2005 | 10.446 | 2004 | 11.031 | 2003 | 11.829 | 2002 | 12.262 | 2001 | 12.171 | 2000 | 12.628 | 1999 | 13.287 | 1998 | 13.444 | 1997 | 13.578 | 1996 | 12.799 | 1995 | 13.374 | 1994 | 13.572 | 1993 | 14.147 | 1992 | 14.977 | 1991 | 16.033 | 1990 | 17.48 | 1989 | 17.744 | 1988 | 17.915 | 1987 | 17.305 | 1986 | 16.749 | 1985 | 16.559 | 1984 | 16.432 | 1983 | 16.355 | 1982 | 15.734 | 1981 | 13.649 | 1980 | 13.706 | 1979 | 14.447 | 1978 | 15.078 | 1977 | 17.364 | 1976 | 19.529 | 1975 | 21.89 | 1974 | 24.31 | 1973 | 26.351 | 1972 | 27.96 | 1971 | 29.008 | 1970 | 29.966 | 1969 | 30.86 | 1968 | 31.644 | 1967 | 32.362 | 1966 | 33.129 | 1965 | 33.933 | 1964 | 34.69 | 1963 | 35.189 | 1962 | 34.443 | 1961 | 33.52 | 1960 | 32.664 |
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