Year | Value | 2021 | 2.192 | 2020 | 2.216 | 2019 | 2.242 | 2018 | 2.26 | 2017 | 2.281 | 2016 | 2.306 | 2015 | 2.338 | 2014 | 2.385 | 2013 | 2.432 | 2012 | 2.487 | 2011 | 2.542 | 2010 | 2.573 | 2009 | 2.607 | 2008 | 2.628 | 2007 | 2.666 | 2006 | 2.686 | 2005 | 2.686 | 2004 | 2.673 | 2003 | 2.661 | 2002 | 2.693 | 2001 | 2.744 | 2000 | 2.845 | 1999 | 2.917 | 1998 | 3.002 | 1997 | 3.099 | 1996 | 3.203 | 1995 | 3.315 | 1994 | 3.432 | 1993 | 3.552 | 1992 | 3.673 | 1991 | 3.794 | 1990 | 3.912 | 1989 | 4.026 | 1988 | 4.138 | 1987 | 4.247 | 1986 | 4.354 | 1985 | 4.46 | 1984 | 4.568 | 1983 | 4.68 | 1982 | 4.795 | 1981 | 4.915 | 1980 | 5.041 | 1979 | 5.171 | 1978 | 5.305 | 1977 | 5.44 | 1976 | 5.575 | 1975 | 5.709 | 1974 | 5.841 | 1973 | 5.968 | 1972 | 6.091 | 1971 | 6.207 | 1970 | 6.316 | 1969 | 6.418 | 1968 | 6.513 | 1967 | 6.6 | 1966 | 6.68 | 1965 | 6.75 | 1964 | 6.81 | 1963 | 6.858 | 1962 | 6.895 | 1961 | 6.923 | 1960 | 6.941 |
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