Year | Value | 2021 | 26.749 | 2020 | 27.53 | 2019 | 28.267 | 2018 | 28.688 | 2017 | 28.932 | 2016 | 30.213 | 2015 | 31.228 | 2014 | 31.432 | 2013 | 31.34 | 2012 | 31.169 | 2011 | 31.274 | 2010 | 31.045 | 2009 | 30.432 | 2008 | 29.587 | 2007 | 28.909 | 2006 | 28.548 | 2005 | 28.48 | 2004 | 28.833 | 2003 | 29.135 | 2002 | 30.167 | 2001 | 30.99 | 2000 | 31.771 | 1999 | 32.306 | 1998 | 33.381 | 1997 | 33.672 | 1996 | 34.88 | 1995 | 36.767 | 1994 | 37.79 | 1993 | 38.123 | 1992 | 39.291 | 1991 | 40.783 | 1990 | 41.936 | 1989 | 42.635 | 1988 | 42.578 | 1987 | 42.188 | 1986 | 41.929 | 1985 | 41.303 | 1984 | 40.987 | 1983 | 40.71 | 1982 | 40.382 | 1981 | 40.341 | 1980 | 40.253 | 1979 | 40.098 | 1978 | 39.942 | 1977 | 39.751 | 1976 | 39.778 | 1975 | 39.875 | 1974 | 39.96 | 1973 | 40.207 | 1972 | 40.756 | 1971 | 41.455 | 1970 | 42.056 | 1969 | 42.56 | 1968 | 43.106 | 1967 | 43.83 | 1966 | 44.776 | 1965 | 45.93 | 1964 | 47.197 | 1963 | 48.42 | 1962 | 49.429 | 1961 | 50.09 | 1960 | 50.327 |
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