Year | Value | 2021 | 53.07 | 2020 | 53.323 | 2019 | 53.165 | 2018 | 52.77 | 2017 | 52.589 | 2016 | 52.229 | 2015 | 52.202 | 2014 | 52.196 | 2013 | 52.115 | 2012 | 51.896 | 2011 | 51.791 | 2010 | 51.404 | 2009 | 51.242 | 2008 | 50.773 | 2007 | 50.819 | 2006 | 50.575 | 2005 | 50.255 | 2004 | 49.78 | 2003 | 49.54 | 2002 | 49.024 | 2001 | 48.689 | 2000 | 48.328 | 1999 | 47.826 | 1998 | 47.226 | 1997 | 47.273 | 1996 | 47.171 | 1995 | 47.056 | 1994 | 47.026 | 1993 | 47.438 | 1992 | 47.28 | 1991 | 47.27 | 1990 | 47.554 | 1989 | 47.643 | 1988 | 47.477 | 1987 | 47.344 | 1986 | 47.148 | 1985 | 47.551 | 1984 | 47.659 | 1983 | 47.735 | 1982 | 47.62 | 1981 | 47.504 | 1980 | 47.498 | 1979 | 47.265 | 1978 | 47.104 | 1977 | 46.535 | 1976 | 45.563 | 1975 | 44.407 | 1974 | 43.478 | 1973 | 42.693 | 1972 | 42.063 | 1971 | 41.285 | 1970 | 40.658 | 1969 | 40.263 | 1968 | 40.139 | 1967 | 39.309 | 1966 | 39.825 | 1965 | 39.794 | 1964 | 39.633 | 1963 | 39.331 | 1962 | 38.952 | 1961 | 38.874 | 1960 | 38.553 |
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