| Year | Value | | 2014 | 2,309.3665025558 | | 2013 | 2,533.2528292711 | | 2012 | 2,118.3277760558 | | 2011 | 2,205.7039200467 | | 2010 | 1,943.3433538584 | | 2009 | 1,835.6840724176 | | 2008 | 1,617.7441562046 | | 2007 | 1,213.1243693218 | | 2006 | 1,218.3601460562 | | 2005 | 1,722.0728497251 | | 2004 | 1,797.5254869688 | | 2003 | 1,469.2645386786 | | 2002 | 1,578.1659188269 | | 2001 | 1,351.2307964288 | | 2000 | 1,449.647413247 | | 1999 | 1,414.7037839305 | | 1998 | 734.84991353767 | | 1997 | 694.66480279238 | | 1996 | 904.34664032856 | | 1995 | 663.78399540245 | | 1994 | 596.40795925595 | | 1993 | 536.3638250952 | | 1992 | 453.64407387777 | | 1991 | 418.45358899715 | | 1990 | 552.25218481918 | | 1989 | 1,021.3935004429 | | 1988 | 1,005.9395303367 | | 1987 | 1,161.9516766901 | | 1986 | 1,420.6147947073 | | 1985 | 796.35397377597 | | 1984 | 1,018.1002875264 | | 1983 | 1,070.6901644186 | | 1982 | 1,096.8732288945 | | 1981 | 1,123.9681063045 | | 1980 | 1,142.9653551258 | | 1979 | 1,065.7673983663 | | 1978 | 1,098.4831658137 | | 1977 | 1,067.8141557783 | | 1976 | 908.67454726938 | | 1975 | 739.34509327267 | | 1974 | 591.03264338392 | | 1973 | 593.44674566518 | | 1972 | 568.40320160348 | | 1971 | 532.02843152625 |
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