Year | Value | 2021 | 4.753 | 2020 | 5.239 | 2019 | 4.301 | 2018 | 4.282 | 2017 | 4.637 | 2016 | 5.13 | 2015 | 4.961 | 2014 | 5.16 | 2013 | 5.413 | 2012 | 5.505 | 2011 | 5.646 | 2010 | 5.85 | 2009 | 6.07 | 2008 | 6.65 | 2007 | 7.214 | 2006 | 7.214 | 2005 | 6.732 | 2004 | 6.688 | 2003 | 6.474 | 2002 | 5.975 | 2001 | 6.041 | 2000 | 6.172 | 1999 | 6.46 | 1998 | 6.78 | 1997 | 6.718 | 1996 | 6.56 | 1995 | 6.606 | 1994 | 6.575 | 1993 | 6.577 | 1992 | 6.707 | 1991 | 8.541 | 1990 | 10.565 | 1989 | 10.735 | 1988 | 10.824 | 1987 | 9.036 | 1986 | 9.211 | 1985 | 9.342 | 1984 | 9.595 | 1983 | 9.698 | 1982 | 9.894 | 1981 | 10.126 | 1980 | 9.381 | 1979 | 8.308 | 1978 | 8.548 | 1977 | 8.712 | 1976 | 9.021 | 1975 | 10.013 | 1974 | 10.366 | 1973 | 10.045 | 1972 | 10.432 | 1971 | 10.746 | 1970 | 11.172 | 1969 | 11.639 | 1968 | 11.972 | 1967 | 12.226 | 1966 | 12.78 | 1965 | 13.208 | 1964 | 13.767 | 1963 | 14.044 | 1962 | 14.027 | 1961 | 13.788 | 1960 | 13.894 |
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