Year | Value | 2021 | 5.877 | 2020 | 5.852 | 2019 | 5.823 | 2018 | 5.939 | 2017 | 6.169 | 2016 | 6.368 | 2015 | 6.648 | 2014 | 6.99 | 2013 | 7.35 | 2012 | 7.843 | 2011 | 8.319 | 2010 | 8.832 | 2009 | 9.229 | 2008 | 9.687 | 2007 | 10.157 | 2006 | 10.77 | 2005 | 11.637 | 2004 | 12.571 | 2003 | 13.434 | 2002 | 14.083 | 2001 | 14.677 | 2000 | 15.297 | 1999 | 15.844 | 1998 | 16.413 | 1997 | 16.728 | 1996 | 17.08 | 1995 | 17.294 | 1994 | 17.534 | 1993 | 17.746 | 1992 | 17.825 | 1991 | 18.005 | 1990 | 18.094 | 1989 | 18.177 | 1988 | 18.113 | 1987 | 18.181 | 1986 | 18.923 | 1985 | 18.874 | 1984 | 20.078 | 1983 | 20.314 | 1982 | 20.639 | 1981 | 20.981 | 1980 | 21.131 | 1979 | 19.674 | 1978 | 19.497 | 1977 | 19.198 | 1976 | 18.903 | 1975 | 18.568 | 1974 | 18.374 | 1973 | 18.096 | 1972 | 18.068 | 1971 | 18.071 | 1970 | 16.361 | 1969 | 16.407 | 1968 | 16.578 | 1967 | 16.716 | 1966 | 17.095 | 1965 | 17.175 | 1964 | 17.431 | 1963 | 17.771 | 1962 | 18.148 | 1961 | 18.687 | 1960 | 19.285 |
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