| Year | Value | | 2021 | 3,915.615 | | 2020 | 3,898 | | 2019 | 3,904 | | 2018 | 3,817.5 | | 2017 | 3,838 | | 2016 | 3,838 | | 2015 | 3,828 | | 2014 | 3,825 | | 2013 | 3,794 | | 2012 | 3,767 | | 2011 | 3,885 | | 2010 | 3,923 | | 2009 | 3,879 | | 2008 | 5,396 | | 2007 | 5,326 | | 2006 | 5,386 | | 2005 | 5,570 | | 2004 | 5,540 | | 2003 | 5,540 | | 2002 | 5,660 | | 2001 | 5,620 | | 2000 | 5,470 | | 1999 | 5,160 | | 1998 | 3,980 | | 1997 | 3,950 | | 1996 | 3,870 | | 1995 | 3,830 | | 1994 | 3,720 | | 1993 | 3,550 | | 1992 | 3,390 | | 1991 | 3,100 | | 1990 | 2,850 | | 1989 | 2,390 | | 1988 | 2,390 | | 1987 | 2,380 | | 1986 | 2,380 | | 1985 | 2,350 | | 1984 | 2,320 | | 1983 | 2,320 | | 1982 | 2,270 | | 1981 | 2,270 | | 1980 | 2,230 | | 1979 | 2,190 | | 1978 | 2,180 | | 1977 | 2,170 | | 1976 | 2,160 | | 1975 | 2,150 | | 1974 | 2,140 |
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