Year | Value | 2021 | 9.007 | 2020 | 8.973 | 2019 | 8.91 | 2018 | 8.927 | 2017 | 8.85 | 2016 | 8.792 | 2015 | 8.772 | 2014 | 8.797 | 2013 | 8.851 | 2012 | 8.879 | 2011 | 8.952 | 2010 | 9.037 | 2009 | 8.937 | 2008 | 9.026 | 2007 | 8.985 | 2006 | 9.082 | 2005 | 9.218 | 2004 | 9.258 | 2003 | 9.329 | 2002 | 9.296 | 2001 | 9.338 | 2000 | 9.47 | 1999 | 9.509 | 1998 | 9.705 | 1997 | 9.781 | 1996 | 9.735 | 1995 | 9.863 | 1994 | 9.729 | 1993 | 9.638 | 1992 | 9.822 | 1991 | 9.762 | 1990 | 9.701 | 1989 | 9.467 | 1988 | 9.447 | 1987 | 9.236 | 1986 | 9.109 | 1985 | 9.042 | 1984 | 8.696 | 1983 | 8.539 | 1982 | 8.554 | 1981 | 8.343 | 1980 | 8.178 | 1979 | 8.265 | 1978 | 8.366 | 1977 | 8.404 | 1976 | 8.499 | 1975 | 8.482 | 1974 | 8.535 | 1973 | 8.548 | 1972 | 8.543 | 1971 | 8.521 | 1970 | 8.59 | 1969 | 8.293 | 1968 | 8.398 | 1967 | 8.308 | 1966 | 8.255 | 1965 | 8.423 | 1964 | 8.505 | 1963 | 8.672 | 1962 | 8.927 | 1961 | 9.194 | 1960 | 9.474 |
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