Year | Value | 2021 | 7.257 | 2020 | 6.93 | 2019 | 6.769 | 2018 | 6.612 | 2017 | 6.453 | 2016 | 6.462 | 2015 | 6.358 | 2014 | 6.317 | 2013 | 6.399 | 2012 | 6.439 | 2011 | 6.354 | 2010 | 6.412 | 2009 | 6.443 | 2008 | 6.599 | 2007 | 6.598 | 2006 | 6.796 | 2005 | 6.889 | 2004 | 6.916 | 2003 | 6.952 | 2002 | 7.113 | 2001 | 7.316 | 2000 | 7.458 | 1999 | 7.509 | 1998 | 7.463 | 1997 | 7.624 | 1996 | 7.805 | 1995 | 8.078 | 1994 | 8.425 | 1993 | 8.508 | 1992 | 8.715 | 1991 | 8.881 | 1990 | 8.835 | 1989 | 8.714 | 1988 | 8.866 | 1987 | 8.797 | 1986 | 9.069 | 1985 | 8.969 | 1984 | 9.218 | 1983 | 9.121 | 1982 | 9.275 | 1981 | 9.15 | 1980 | 9.03 | 1979 | 8.948 | 1978 | 8.906 | 1977 | 9.114 | 1976 | 9.182 | 1975 | 9.44 | 1974 | 17.101 | 1973 | 9.515 | 1972 | 9.341 | 1971 | 9.24 | 1970 | 9.113 | 1969 | 9.054 | 1968 | 8.87 | 1967 | 8.796 | 1966 | 8.807 | 1965 | 8.864 | 1964 | 10.72 | 1963 | 10.932 | 1962 | 9.425 | 1961 | 9.814 | 1960 | 10.025 |
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