| Year | Value | | 2021 | 6,793 | | 2020 | 6,773 | | 2019 | 6,713 | | 2018 | 6,715.5 | | 2017 | 6,733.2 | | 2016 | 6,710 | | 2015 | 6,650 | | 2014 | 6,620 | | 2013 | 6,600 | | 2012 | 6,580 | | 2011 | 6,510 | | 2010 | 6,400 | | 2009 | 6,630 | | 2008 | 6,630 | | 2007 | 6,771 | | 2006 | 6,790 | | 2005 | 6,530 | | 2004 | 6,383 | | 2003 | 6,270 | | 2002 | 6,160 | | 2001 | 5,980 | | 2000 | 5,950 | | 1999 | 5,825 | | 1998 | 6,260 | | 1997 | 6,220 | | 1996 | 6,180 | | 1995 | 6,090 | | 1994 | 6,070 | | 1993 | 6,060 | | 1992 | 6,060 | | 1991 | 6,060 | | 1990 | 6,050 | | 1989 | 6,040 | | 1988 | 6,040 | | 1987 | 6,040 | | 1986 | 6,000 | | 1985 | 5,990 | | 1984 | 5,980 | | 1983 | 5,980 | | 1982 | 5,980 | | 1981 | 5,980 | | 1980 | 6,010 | | 1979 | 6,130 | | 1978 | 6,190 | | 1977 | 6,250 | | 1976 | 6,300 | | 1975 | 6,350 | | 1974 | 6,400 | | 1973 | 6,450 | | 1972 | 6,350 | | 1971 | 6,300 | | 1970 | 6,250 | | 1969 | 6,200 | | 1968 | 6,160 | | 1967 | 6,060 | | 1966 | 5,960 | | 1965 | 5,960 | | 1964 | 5,800 | | 1963 | 5,700 | | 1962 | 5,700 | | 1961 | 5,620 |
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