Year | Value | 2021 | 1.797 | 2020 | 1.814 | 2019 | 1.838 | 2018 | 1.873 | 2017 | 1.932 | 2016 | 2.025 | 2015 | 2.099 | 2014 | 2.12 | 2013 | 2.112 | 2012 | 2.12 | 2011 | 2.101 | 2010 | 2.133 | 2009 | 2.154 | 2008 | 2.137 | 2007 | 2.081 | 2006 | 2.055 | 2005 | 2.065 | 2004 | 2.087 | 2003 | 2.14 | 2002 | 2.215 | 2001 | 2.298 | 2000 | 2.34 | 1999 | 2.375 | 1998 | 2.416 | 1997 | 2.489 | 1996 | 2.569 | 1995 | 2.665 | 1994 | 2.74 | 1993 | 2.802 | 1992 | 2.829 | 1991 | 2.823 | 1990 | 2.825 | 1989 | 2.836 | 1988 | 2.862 | 1987 | 2.927 | 1986 | 3.015 | 1985 | 3.159 | 1984 | 3.333 | 1983 | 3.569 | 1982 | 3.723 | 1981 | 3.814 | 1980 | 3.905 | 1979 | 4.158 | 1978 | 4.334 | 1977 | 4.498 | 1976 | 4.729 | 1975 | 4.975 | 1974 | 5.22 | 1973 | 5.459 | 1972 | 5.678 | 1971 | 5.887 | 1970 | 6.087 | 1969 | 6.276 | 1968 | 6.449 | 1967 | 6.594 | 1966 | 6.71 | 1965 | 6.823 | 1964 | 6.928 | 1963 | 7.022 | 1962 | 7.13 | 1961 | 7.227 | 1960 | 7.286 |
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