Year | Value | 2021 | 10.473 | 2020 | 10.339 | 2019 | 10.822 | 2018 | 11.605 | 2017 | 12.579 | 2016 | 13.64 | 2015 | 14.216 | 2014 | 14.082 | 2013 | 14.197 | 2012 | 14.196 | 2011 | 14.223 | 2010 | 14.264 | 2009 | 14.34 | 2008 | 14.455 | 2007 | 14.618 | 2006 | 14.837 | 2005 | 15.103 | 2004 | 15.075 | 2003 | 15.204 | 2002 | 15.545 | 2001 | 15.52 | 2000 | 15.768 | 1999 | 16.211 | 1998 | 16.535 | 1997 | 17.057 | 1996 | 17.342 | 1995 | 17.608 | 1994 | 17.687 | 1993 | 17.511 | 1992 | 17.65 | 1991 | 17.758 | 1990 | 17.62 | 1989 | 18.189 | 1988 | 18.09 | 1987 | 17.421 | 1986 | 17.771 | 1985 | 17.808 | 1984 | 17.765 | 1983 | 17.867 | 1982 | 18.099 | 1981 | 18.284 | 1980 | 18.422 | 1979 | 19.268 | 1978 | 20.039 | 1977 | 20.546 | 1976 | 21.32 | 1975 | 21.443 | 1974 | 21.082 | 1973 | 20.385 | 1972 | 20.171 | 1971 | 19.912 | 1970 | 19.461 | 1969 | 19.949 | 1968 | 20.198 | 1967 | 20.428 | 1966 | 20.818 | 1965 | 21.126 | 1964 | 21.452 | 1963 | 21.781 | 1962 | 21.804 | 1961 | 21.798 | 1960 | 21.784 |
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