Year | Value | 2021 | 1.7 | 2020 | 1.581 | 2019 | 1.657 | 2018 | 1.74 | 2017 | 1.741 | 2016 | 1.752 | 2015 | 1.814 | 2014 | 1.826 | 2013 | 1.855 | 2012 | 1.92 | 2011 | 1.926 | 2010 | 1.928 | 2009 | 1.971 | 2008 | 1.984 | 2007 | 1.959 | 2006 | 1.908 | 2005 | 1.807 | 2004 | 1.768 | 2003 | 1.748 | 2002 | 1.756 | 2001 | 1.739 | 2000 | 1.756 | 1999 | 1.755 | 1998 | 1.762 | 1997 | 1.778 | 1996 | 1.796 | 1995 | 1.822 | 1994 | 1.842 | 1993 | 1.859 | 1992 | 1.888 | 1991 | 1.849 | 1990 | 1.902 | 1989 | 1.838 | 1988 | 1.831 | 1987 | 1.845 | 1986 | 1.868 | 1985 | 1.923 | 1984 | 1.84 | 1983 | 1.924 | 1982 | 1.929 | 1981 | 1.935 | 1980 | 1.891 | 1979 | 1.907 | 1978 | 1.949 | 1977 | 2.007 | 1976 | 2.06 | 1975 | 2.148 | 1974 | 2.397 | 1973 | 2.491 | 1972 | 2.744 | 1971 | 2.961 | 1970 | 2.859 | 1969 | 2.886 | 1968 | 2.888 | 1967 | 2.848 | 1966 | 2.881 | 1965 | 2.977 | 1964 | 3.146 | 1963 | 3.332 | 1962 | 3.442 | 1961 | 3.54 | 1960 | 3.453 |
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