Year | Value | 2021 | 6.504 | 2020 | 5.337 | 2019 | 4.892 | 2018 | 4.995 | 2017 | 5.015 | 2016 | 5.038 | 2015 | 5.071 | 2014 | 5.071 | 2013 | 5.112 | 2012 | 5.171 | 2011 | 5.233 | 2010 | 5.296 | 2009 | 5.329 | 2008 | 5.377 | 2007 | 5.419 | 2006 | 5.469 | 2005 | 5.666 | 2004 | 5.625 | 2003 | 5.727 | 2002 | 5.859 | 2001 | 6.013 | 2000 | 6.19 | 1999 | 6.419 | 1998 | 6.747 | 1997 | 7.006 | 1996 | 7.33 | 1995 | 7.679 | 1994 | 7.976 | 1993 | 8.143 | 1992 | 8.334 | 1991 | 8.435 | 1990 | 8.595 | 1989 | 8.681 | 1988 | 8.861 | 1987 | 9.136 | 1986 | 9.445 | 1985 | 9.751 | 1984 | 10.104 | 1983 | 10.481 | 1982 | 14.866 | 1981 | 11.691 | 1980 | 11.755 | 1979 | 11.731 | 1978 | 11.885 | 1977 | 12.018 | 1976 | 15.783 | 1975 | 12.602 | 1974 | 13.02 | 1973 | 13.604 | 1972 | 14.373 | 1971 | 15.067 | 1970 | 15.729 | 1969 | 16.339 | 1968 | 16.577 | 1967 | 16.872 | 1966 | 17.09 | 1965 | 17.13 | 1964 | 17.296 | 1963 | 17.579 | 1962 | 17.94 | 1961 | 18.396 | 1960 | 18.949 |
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