Year | Value | 2021 | 9.313 | 2020 | 9.078 | 2019 | 8.878 | 2018 | 8.721 | 2017 | 8.502 | 2016 | 8.327 | 2015 | 8.088 | 2014 | 8.183 | 2013 | 8.305 | 2012 | 8.468 | 2011 | 8.609 | 2010 | 8.71 | 2009 | 8.95 | 2008 | 9.338 | 2007 | 9.148 | 2006 | 8.843 | 2005 | 8.501 | 2004 | 8.189 | 2003 | 7.899 | 2002 | 11.138 | 2001 | 10.97 | 2000 | 10.763 | 1999 | 10.567 | 1998 | 10.328 | 1997 | 10.129 | 1996 | 9.988 | 1995 | 9.856 | 1994 | 5.89 | 1993 | 5.263 | 1992 | 5.554 | 1991 | 5.62 | 1990 | 5.578 | 1989 | 5.559 | 1988 | 5.57 | 1987 | 5.62 | 1986 | 5.649 | 1985 | 5.736 | 1984 | 5.833 | 1983 | 5.945 | 1982 | 6.065 | 1981 | 6.194 | 1980 | 6.32 | 1979 | 6.451 | 1978 | 6.583 | 1977 | 6.756 | 1976 | 6.957 | 1975 | 7.247 | 1974 | 7.513 | 1973 | 7.855 | 1972 | 8.265 | 1971 | 8.561 | 1970 | 8.915 | 1969 | 9.27 | 1968 | 9.703 | 1967 | 10.144 | 1966 | 10.433 | 1965 | 10.765 | 1964 | 11.096 | 1963 | 11.357 | 1962 | 11.475 | 1961 | 11.649 | 1960 | 11.909 |
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