Year | Value | 2021 | 6.613 | 2020 | 6.366 | 2019 | 6.505 | 2018 | 6.755 | 2017 | 6.91 | 2016 | 7.135 | 2015 | 7.513 | 2014 | 7.465 | 2013 | 7.584 | 2012 | 7.604 | 2011 | 7.762 | 2010 | 8.008 | 2009 | 8.266 | 2008 | 8.539 | 2007 | 8.785 | 2006 | 9.096 | 2005 | 9.378 | 2004 | 9.598 | 2003 | 9.626 | 2002 | 9.785 | 2001 | 9.956 | 2000 | 10.256 | 1999 | 10.511 | 1998 | 10.599 | 1997 | 10.802 | 1996 | 11.139 | 1995 | 11.543 | 1994 | 12.03 | 1993 | 12.337 | 1992 | 12.701 | 1991 | 13.063 | 1990 | 13.548 | 1989 | 13.874 | 1988 | 14.236 | 1987 | 14.629 | 1986 | 14.943 | 1985 | 15.324 | 1984 | 15.688 | 1983 | 16.05 | 1982 | 16.408 | 1981 | 16.853 | 1980 | 17.307 | 1979 | 18.092 | 1978 | 18.678 | 1977 | 18.89 | 1976 | 19.182 | 1975 | 19.002 | 1974 | 19.255 | 1973 | 19.925 | 1972 | 20.08 | 1971 | 20.272 | 1970 | 20.57 | 1969 | 20.808 | 1968 | 20.962 | 1967 | 21.23 | 1966 | 21.635 | 1965 | 21.65 | 1964 | 21.96 | 1963 | 22.206 | 1962 | 21.753 | 1961 | 22.452 | 1960 | 22.677 |
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