Year | Value | 2021 | 18.432 | 2020 | 18.78 | 2019 | 19.291 | 2018 | 19.762 | 2017 | 19.993 | 2016 | 20.258 | 2015 | 20.596 | 2014 | 20.867 | 2013 | 21.166 | 2012 | 21.454 | 2011 | 21.792 | 2010 | 22.038 | 2009 | 22.132 | 2008 | 21.947 | 2007 | 21.705 | 2006 | 21.865 | 2005 | 22.485 | 2004 | 22.972 | 2003 | 23.425 | 2002 | 23.868 | 2001 | 24.317 | 2000 | 24.842 | 1999 | 25.006 | 1998 | 25.219 | 1997 | 26.079 | 1996 | 27.026 | 1995 | 27.778 | 1994 | 28.607 | 1993 | 29.25 | 1992 | 29.802 | 1991 | 30.37 | 1990 | 30.887 | 1989 | 31.29 | 1988 | 31.288 | 1987 | 31.326 | 1986 | 31.624 | 1985 | 31.971 | 1984 | 32.615 | 1983 | 33.087 | 1982 | 33.183 | 1981 | 33.65 | 1980 | 34.258 | 1979 | 34.876 | 1978 | 35.414 | 1977 | 36.111 | 1976 | 36.867 | 1975 | 37.549 | 1974 | 38.501 | 1973 | 39.613 | 1972 | 40.359 | 1971 | 41.184 | 1970 | 42.061 | 1969 | 42.919 | 1968 | 43.983 | 1967 | 45.407 | 1966 | 46.69 | 1965 | 47.437 | 1964 | 48.465 | 1963 | 49.47 | 1962 | 50.461 | 1961 | 51.39 | 1960 | 52.229 |
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