Year | Value | 2021 | 16.425 | 2020 | 16.649 | 2019 | 16.91 | 2018 | 17.179 | 2017 | 17.519 | 2016 | 18.017 | 2015 | 18.448 | 2014 | 18.954 | 2013 | 19.417 | 2012 | 20.093 | 2011 | 20.345 | 2010 | 20.158 | 2009 | 20.383 | 2008 | 20.702 | 2007 | 20.954 | 2006 | 20.784 | 2005 | 20.735 | 2004 | 20.701 | 2003 | 20.874 | 2002 | 21.174 | 2001 | 21.548 | 2000 | 21.86 | 1999 | 22.193 | 1998 | 22.826 | 1997 | 23.441 | 1996 | 23.648 | 1995 | 23.791 | 1994 | 24.014 | 1993 | 24.263 | 1992 | 24.63 | 1991 | 25.367 | 1990 | 25.515 | 1989 | 26.306 | 1988 | 26.971 | 1987 | 27.445 | 1986 | 28.007 | 1985 | 29.178 | 1984 | 30.719 | 1983 | 31.591 | 1982 | 32.446 | 1981 | 32.95 | 1980 | 33.617 | 1979 | 34.224 | 1978 | 34.749 | 1977 | 35.177 | 1976 | 35.781 | 1975 | 36.456 | 1974 | 36.953 | 1973 | 37.858 | 1972 | 38.417 | 1971 | 39.104 | 1970 | 39.899 | 1969 | 40.631 | 1968 | 41.264 | 1967 | 42.023 | 1966 | 42.712 | 1965 | 43.286 | 1964 | 43.626 | 1963 | 43.949 | 1962 | 44.213 | 1961 | 44.388 | 1960 | 44.461 |
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