Year | Value | 2021 | 50.845 | 2020 | 51.218 | 2019 | 51.664 | 2018 | 51.372 | 2017 | 50.898 | 2016 | 50.867 | 2015 | 50.09 | 2014 | 49.808 | 2013 | 49.431 | 2012 | 49.255 | 2011 | 48.76 | 2010 | 48.388 | 2009 | 48.045 | 2008 | 47.788 | 2007 | 47.521 | 2006 | 47.083 | 2005 | 47.33 | 2004 | 47.158 | 2003 | 47.307 | 2002 | 47.012 | 2001 | 46.888 | 2000 | 46.325 | 1999 | 46.399 | 1998 | 46.203 | 1997 | 46.231 | 1996 | 45.97 | 1995 | 45.688 | 1994 | 45.365 | 1993 | 45.181 | 1992 | 44.698 | 1991 | 44.437 | 1990 | 41.782 | 1989 | 44.033 | 1988 | 44.081 | 1987 | 38.766 | 1986 | 42.954 | 1985 | 43.018 | 1984 | 42.135 | 1983 | 41.728 | 1982 | 41.481 | 1981 | 41.105 | 1980 | 41.041 | 1979 | 40.811 | 1978 | 40.541 | 1977 | 40.248 | 1976 | 40.035 | 1975 | 40.303 | 1974 | 40.168 | 1973 | 40.064 | 1972 | 39.267 | 1971 | 38.216 | 1970 | 38.559 | 1969 | 38.272 | 1968 | 37.952 | 1967 | 37.46 | 1966 | 37.139 | 1965 | 37.565 | 1964 | 37.793 | 1963 | 37.558 | 1962 | 37.382 | 1961 | 37.098 | 1960 | 36.811 |
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