Year | Value | 2021 | 2.325 | 2020 | 2.344 | 2019 | 2.375 | 2018 | 2.441 | 2017 | 2.493 | 2016 | 2.528 | 2015 | 2.564 | 2014 | 2.59 | 2013 | 2.609 | 2012 | 2.636 | 2011 | 2.627 | 2010 | 2.604 | 2009 | 2.613 | 2008 | 2.631 | 2007 | 2.63 | 2006 | 2.636 | 2005 | 2.665 | 2004 | 2.691 | 2003 | 2.679 | 2002 | 2.698 | 2001 | 2.72 | 2000 | 2.744 | 1999 | 2.767 | 1998 | 2.789 | 1997 | 2.81 | 1996 | 2.83 | 1995 | 2.852 | 1994 | 2.877 | 1993 | 2.909 | 1992 | 2.95 | 1991 | 2.999 | 1990 | 3.096 | 1989 | 3.148 | 1988 | 3.198 | 1987 | 3.27 | 1986 | 3.352 | 1985 | 3.431 | 1984 | 3.523 | 1983 | 3.611 | 1982 | 3.67 | 1981 | 3.741 | 1980 | 3.812 | 1979 | 3.895 | 1978 | 3.999 | 1977 | 4.132 | 1976 | 4.273 | 1975 | 4.424 | 1974 | 4.575 | 1973 | 4.739 | 1972 | 4.907 | 1971 | 5.048 | 1970 | 5.171 | 1969 | 5.304 | 1968 | 5.432 | 1967 | 5.546 | 1966 | 5.649 | 1965 | 5.728 | 1964 | 5.808 | 1963 | 5.865 | 1962 | 5.872 | 1961 | 5.865 | 1960 | 5.844 |
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