Year | Value | 2021 | 7.168 | 2020 | 7.06 | 2019 | 6.765 | 2018 | 6.843 | 2017 | 6.89 | 2016 | 7.036 | 2015 | 7.097 | 2014 | 7.274 | 2013 | 7.333 | 2012 | 7.479 | 2011 | 7.524 | 2010 | 7.599 | 2009 | 7.703 | 2008 | 7.733 | 2007 | 7.798 | 2006 | 7.831 | 2005 | 8.402 | 2004 | 8.177 | 2003 | 8.311 | 2002 | 8.454 | 2001 | 8.583 | 2000 | 8.77 | 1999 | 9.023 | 1998 | 9.353 | 1997 | 9.654 | 1996 | 9.852 | 1995 | 10.194 | 1994 | 10.215 | 1993 | 10.43 | 1992 | 10.489 | 1991 | 10.543 | 1990 | 10.731 | 1989 | 11.013 | 1988 | 11.199 | 1987 | 11.383 | 1986 | 11.257 | 1985 | 11.351 | 1984 | 11.415 | 1983 | 11.608 | 1982 | 11.825 | 1981 | 11.946 | 1980 | 12.109 | 1979 | 12.309 | 1978 | 12.502 | 1977 | 12.735 | 1976 | 12.817 | 1975 | 12.95 | 1974 | 13.205 | 1973 | 13.246 | 1972 | 13.404 | 1971 | 16.162 | 1970 | 13.794 | 1969 | 14.395 | 1968 | 14.96 | 1967 | 15.615 | 1966 | 16.323 | 1965 | 17.286 | 1964 | 17.927 | 1963 | 18.673 | 1962 | 19.486 | 1961 | 20.184 | 1960 | 20.909 |
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