Year | Value | 2021 | 7.474 | 2020 | 7.562 | 2019 | 7.352 | 2018 | 7.648 | 2017 | 7.772 | 2016 | 8.18 | 2015 | 8.553 | 2014 | 8.798 | 2013 | 9.178 | 2012 | 9.625 | 2011 | 10.094 | 2010 | 10.538 | 2009 | 10.92 | 2008 | 11.316 | 2007 | 11.871 | 2006 | 12.366 | 2005 | 12.841 | 2004 | 13.369 | 2003 | 13.984 | 2002 | 14.501 | 2001 | 15.316 | 2000 | 15.907 | 1999 | 15.965 | 1998 | 16.646 | 1997 | 17.626 | 1996 | 18.599 | 1995 | 18.823 | 1994 | 18.937 | 1993 | 24.9 | 1992 | 19.519 | 1991 | 19.393 | 1990 | 19.067 | 1989 | 18.639 | 1988 | 20.561 | 1987 | 17.569 | 1986 | 17.269 | 1985 | 17.172 | 1984 | 17.373 | 1983 | 17.82 | 1982 | 18.467 | 1981 | 19.091 | 1980 | 19.821 | 1979 | 20.408 | 1978 | 20.999 | 1977 | 21.197 | 1976 | 21.478 | 1975 | 21.573 | 1974 | 21.549 | 1973 | 26.085 | 1972 | 39.912 | 1971 | 21.692 | 1970 | 21.636 | 1969 | 21.713 | 1968 | 21.318 | 1967 | 21.296 | 1966 | 21.133 | 1965 | 22.226 | 1964 | 20.737 | 1963 | 20.97 | 1962 | 21.2 | 1961 | 21.409 | 1960 | 21.657 |
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