Year | Value | 2021 | 2.415 | 2020 | 2.448 | 2019 | 2.485 | 2018 | 2.517 | 2017 | 2.518 | 2016 | 2.534 | 2015 | 2.558 | 2014 | 2.595 | 2013 | 2.668 | 2012 | 2.748 | 2011 | 2.41 | 2010 | 2.397 | 2009 | 2.434 | 2008 | 2.481 | 2007 | 2.514 | 2006 | 2.554 | 2005 | 2.592 | 2004 | 2.631 | 2003 | 2.666 | 2002 | 2.687 | 2001 | 2.705 | 2000 | 2.714 | 1999 | 2.722 | 1998 | 2.727 | 1997 | 2.734 | 1996 | 2.736 | 1995 | 2.742 | 1994 | 2.763 | 1993 | 2.778 | 1992 | 2.81 | 1991 | 2.845 | 1990 | 2.894 | 1989 | 2.952 | 1988 | 3.018 | 1987 | 3.084 | 1986 | 3.169 | 1985 | 3.266 | 1984 | 3.381 | 1983 | 3.522 | 1982 | 3.7 | 1981 | 3.918 | 1980 | 4.12 | 1979 | 4.307 | 1978 | 4.497 | 1977 | 4.706 | 1976 | 4.905 | 1975 | 5.094 | 1974 | 5.276 | 1973 | 5.431 | 1972 | 5.559 | 1971 | 5.654 | 1970 | 5.734 | 1969 | 5.795 | 1968 | 5.842 | 1967 | 5.864 | 1966 | 5.892 | 1965 | 5.916 | 1964 | 5.933 | 1963 | 5.94 | 1962 | 5.947 | 1961 | 5.957 | 1960 | 5.948 |
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