Year | Value | 2021 | 15.877 | 2020 | 16.213 | 2019 | 16.888 | 2018 | 17.832 | 2017 | 18.502 | 2016 | 18.898 | 2015 | 19.201 | 2014 | 19.507 | 2013 | 19.827 | 2012 | 20.143 | 2011 | 20.466 | 2010 | 20.805 | 2009 | 21.117 | 2008 | 21.433 | 2007 | 21.744 | 2006 | 22.06 | 2005 | 22.334 | 2004 | 22.579 | 2003 | 22.869 | 2002 | 23.208 | 2001 | 23.53 | 2000 | 23.9 | 1999 | 24.27 | 1998 | 24.598 | 1997 | 24.991 | 1996 | 25.41 | 1995 | 25.871 | 1994 | 26.424 | 1993 | 26.99 | 1992 | 27.598 | 1991 | 28.219 | 1990 | 28.834 | 1989 | 29.418 | 1988 | 29.98 | 1987 | 30.45 | 1986 | 30.811 | 1985 | 30.821 | 1984 | 31.208 | 1983 | 31.634 | 1982 | 32.126 | 1981 | 32.724 | 1980 | 33.25 | 1979 | 33.741 | 1978 | 34.109 | 1977 | 34.462 | 1976 | 34.773 | 1975 | 35.037 | 1974 | 35.364 | 1973 | 35.786 | 1972 | 36.189 | 1971 | 36.762 | 1970 | 37.49 | 1969 | 38.256 | 1968 | 39.017 | 1967 | 39.752 | 1966 | 40.478 | 1965 | 41.207 | 1964 | 41.949 | 1963 | 42.716 | 1962 | 43.437 | 1961 | 44.172 | 1960 | 44.877 |
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