| Year | Value | | 2014 | 4,115.6302011884 | | 2013 | 4,075.3429300187 | | 2012 | 4,093.4593570975 | | 2011 | 4,096.8940841095 | | 2010 | 4,017.4122467389 | | 2009 | 3,840.5360281048 | | 2008 | 4,048.765487377 | | 2007 | 3,984.5889989128 | | 2006 | 3,888.5255986385 | | 2005 | 3,739.6534658829 | | 2004 | 3,676.626454519 | | 2003 | 3,588.3234614156 | | 2002 | 3,454.6359405792 | | 2001 | 3,430.7250542474 | | 2000 | 3,341.7268012681 | | 1999 | 3,281.6145166385 | | 1998 | 3,337.0151908204 | | 1997 | 3,383.4325456981 | | 1996 | 3,426.0151364919 | | 1995 | 3,299.3900490611 | | 1994 | 3,172.2227183875 | | 1993 | 3,148.0274736018 | | 1992 | 3,217.3401324807 | | 1991 | 3,469.5921905733 | | 1990 | 3,744.0517302347 | | 1989 | 3,948.0251748755 | | 1988 | 3,934.0784561407 | | 1987 | 3,867.9784566496 | | 1986 | 3,762.245099864 | | 1985 | 3,646.653521042 | | 1984 | 3,562.9110680866 | | 1983 | 3,436.8255607715 | | 1982 | 3,320.0518523441 | | 1981 | 3,279.0777951644 | | 1980 | 3,307.3218246269 | | 1979 | 3,161.2682993216 | | 1978 | 3,124.9460324923 | | 1977 | 2,984.6592918248 | | 1976 | 2,848.027630227 | | 1975 | 2,683.047694575 | | 1974 | 2,522.6815519425 | | 1973 | 2,389.9888684171 | | 1972 | 2,243.5373376912 | | 1971 | 2,088.953932085 |
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