Year | Value | 2021 | 7.44 | 2020 | 7.466 | 2019 | 7.003 | 2018 | 7.248 | 2017 | 7.446 | 2016 | 7.707 | 2015 | 7.979 | 2014 | 8.301 | 2013 | 8.652 | 2012 | 8.581 | 2011 | 8.454 | 2010 | 8.327 | 2009 | 8.241 | 2008 | 8.204 | 2007 | 8.275 | 2006 | 8.418 | 2005 | 8.512 | 2004 | 8.534 | 2003 | 8.645 | 2002 | 8.704 | 2001 | 8.766 | 2000 | 8.856 | 1999 | 8.973 | 1998 | 9.087 | 1997 | 9.203 | 1996 | 9.426 | 1995 | 9.39 | 1994 | 9.373 | 1993 | 9.36 | 1992 | 9.375 | 1991 | 9.52 | 1990 | 9.614 | 1989 | 9.844 | 1988 | 9.963 | 1987 | 10.286 | 1986 | 10.644 | 1985 | 10.937 | 1984 | 11.237 | 1983 | 11.56 | 1982 | 11.843 | 1981 | 12.211 | 1980 | 12.56 | 1979 | 12.921 | 1978 | 13.322 | 1977 | 13.642 | 1976 | 13.932 | 1975 | 14.122 | 1974 | 14.4 | 1973 | 14.574 | 1972 | 14.721 | 1971 | 14.89 | 1970 | 15.11 | 1969 | 15.384 | 1968 | 15.775 | 1967 | 16.214 | 1966 | 16.622 | 1965 | 17.035 | 1964 | 17.407 | 1963 | 17.87 | 1962 | 18.257 | 1961 | 18.62 | 1960 | 19.014 |
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