Year | Value | 2021 | 8.056 | 2020 | 7.456 | 2019 | 7.29 | 2018 | 7.305 | 2017 | 7.294 | 2016 | 7.34 | 2015 | 7.361 | 2014 | 7.304 | 2013 | 7.399 | 2012 | 7.453 | 2011 | 7.428 | 2010 | 7.57 | 2009 | 7.718 | 2008 | 8.087 | 2007 | 8.457 | 2006 | 8.748 | 2005 | 9.147 | 2004 | 9.61 | 2003 | 9.995 | 2002 | 10.332 | 2001 | 10.587 | 2000 | 10.677 | 1999 | 10.697 | 1998 | 10.743 | 1997 | 10.65 | 1996 | 10.543 | 1995 | 10.387 | 1994 | 10.153 | 1993 | 10.036 | 1992 | 9.803 | 1991 | 9.527 | 1990 | 9.31 | 1989 | 9.162 | 1988 | 8.999 | 1987 | 8.849 | 1986 | 8.818 | 1985 | 8.751 | 1984 | 8.76 | 1983 | 8.793 | 1982 | 8.937 | 1981 | 9.001 | 1980 | 9.97 | 1979 | 10.395 | 1978 | 10.838 | 1977 | 11.197 | 1976 | 11.604 | 1975 | 11.832 | 1974 | 12.111 | 1973 | 12.328 | 1972 | 12.807 | 1971 | 13.317 | 1970 | 13.802 | 1969 | 14.197 | 1968 | 14.581 | 1967 | 14.951 | 1966 | 15.339 | 1965 | 15.733 | 1964 | 16.129 | 1963 | 16.644 | 1962 | 17.216 | 1961 | 17.869 | 1960 | 18.647 |
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