Year | Value | 2021 | 2.623 | 2020 | 2.687 | 2019 | 2.776 | 2018 | 2.883 | 2017 | 2.937 | 2016 | 2.946 | 2015 | 2.959 | 2014 | 2.956 | 2013 | 2.949 | 2012 | 2.929 | 2011 | 2.94 | 2010 | 2.943 | 2009 | 2.841 | 2008 | 2.806 | 2007 | 2.813 | 2006 | 2.921 | 2005 | 3.049 | 2004 | 3.2 | 2003 | 3.346 | 2002 | 3.501 | 2001 | 3.69 | 2000 | 3.893 | 1999 | 4.126 | 1998 | 4.344 | 1997 | 4.616 | 1996 | 4.895 | 1995 | 5.19 | 1994 | 5.472 | 1993 | 5.761 | 1992 | 6.045 | 1991 | 6.339 | 1990 | 6.606 | 1989 | 6.874 | 1988 | 7.135 | 1987 | 7.371 | 1986 | 7.584 | 1985 | 7.756 | 1984 | 7.9 | 1983 | 8.022 | 1982 | 8.104 | 1981 | 8.125 | 1980 | 8.096 | 1979 | 8.042 | 1978 | 7.989 | 1977 | 7.939 | 1976 | 7.862 | 1975 | 7.747 | 1974 | 7.617 | 1973 | 7.504 | 1972 | 7.414 | 1971 | 7.35 | 1970 | 7.311 | 1969 | 7.293 | 1968 | 7.286 | 1967 | 7.282 | 1966 | 7.277 | 1965 | 7.271 | 1964 | 7.263 | 1963 | 7.256 | 1962 | 7.251 | 1961 | 7.248 | 1960 | 7.247 |
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