Year | Value | 2021 | 1.58 | 2020 | 1.569 | 2019 | 1.468 | 2018 | 1.371 | 2017 | 1.485 | 2016 | 1.458 | 2015 | 1.567 | 2014 | 1.526 | 2013 | 1.537 | 2012 | 1.655 | 2011 | 1.746 | 2010 | 1.785 | 2009 | 2.006 | 2008 | 2.042 | 2007 | 1.86 | 2006 | 1.831 | 2005 | 1.832 | 2004 | 1.852 | 2003 | 1.887 | 2002 | 1.94 | 2001 | 2.018 | 2000 | 2.196 | 1999 | 1.956 | 1998 | 2.017 | 1997 | 2.19 | 1996 | 2.266 | 1995 | 2.159 | 1994 | 2.069 | 1993 | 2.036 | 1992 | 2.126 | 1991 | 2.036 | 1990 | 2.249 | 1989 | 2.199 | 1988 | 2.132 | 1987 | 2.067 | 1986 | 2.032 | 1985 | 2.151 | 1984 | 2.038 | 1983 | 2.116 | 1982 | 2.087 | 1981 | 2.166 | 1980 | 2.311 | 1979 | 2.632 | 1978 | 2.573 | 1977 | 2.784 | 1976 | 2.78 | 1975 | 2.77 | 1974 | 2.932 | 1973 | 3.126 | 1972 | 3.287 | 1971 | 3.455 | 1970 | 3.628 | 1969 | 3.829 | 1968 | 4.014 | 1967 | 4.178 | 1966 | 4.322 | 1965 | 4.416 | 1964 | 4.484 | 1963 | 4.536 | 1962 | 4.547 | 1961 | 4.559 | 1960 | 4.602 |
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