Year | Value | 2021 | 1.493 | 2020 | 1.477 | 2019 | 1.546 | 2018 | 1.658 | 2017 | 1.796 | 2016 | 1.945 | 2015 | 2.023 | 2014 | 1.998 | 2013 | 2.01 | 2012 | 2.006 | 2011 | 2.008 | 2010 | 2.011 | 2009 | 2.018 | 2008 | 2.03 | 2007 | 2.048 | 2006 | 2.07 | 2005 | 2.097 | 2004 | 2.09 | 2003 | 2.101 | 2002 | 2.142 | 2001 | 2.132 | 2000 | 2.168 | 1999 | 2.22 | 1998 | 2.262 | 1997 | 2.328 | 1996 | 2.364 | 1995 | 2.401 | 1994 | 2.415 | 1993 | 2.397 | 1992 | 2.423 | 1991 | 2.446 | 1990 | 2.433 | 1989 | 2.516 | 1988 | 2.506 | 1987 | 2.416 | 1986 | 2.472 | 1985 | 2.48 | 1984 | 2.476 | 1983 | 2.492 | 1982 | 2.53 | 1981 | 2.562 | 1980 | 2.587 | 1979 | 2.712 | 1978 | 2.826 | 1977 | 2.896 | 1976 | 3.008 | 1975 | 3.018 | 1974 | 2.959 | 1973 | 2.856 | 1972 | 2.816 | 1971 | 2.77 | 1970 | 2.698 | 1969 | 2.753 | 1968 | 2.771 | 1967 | 2.784 | 1966 | 2.819 | 1965 | 2.84 | 1964 | 2.863 | 1963 | 2.884 | 1962 | 2.866 | 1961 | 2.846 | 1960 | 2.827 |
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