| Year | Value | | 2014 | 6,661.1013875744 | | 2013 | 6,434.9367577108 | | 2012 | 6,217.2420278011 | | 2011 | 6,006.2534330502 | | 2010 | 5,828.5636490496 | | 2009 | 5,389.7006189734 | | 2008 | 5,389.8505388056 | | 2007 | 5,359.382638402 | | 2006 | 5,022.8081680912 | | 2005 | 4,871.1721417746 | | 2004 | 4,453.5150590814 | | 2003 | 4,525.1442874578 | | 2002 | 3,875.2893836685 | | 2001 | 3,896.7044608152 | | 2000 | 3,798.2199409549 | | 1999 | 3,631.3272241032 | | 1998 | 3,592.2429931981 | | 1997 | 3,479.8216619847 | | 1996 | 3,114.735875575 | | 1995 | 2,975.9401508768 | | 1994 | 2,774.719089468 | | 1993 | 2,706.3913185273 | | 1992 | 2,739.7857023949 | | 1991 | 2,552.0598264881 | | 1990 | 2,588.1985096145 | | 1989 | 2,432.7142754794 | | 1988 | 2,536.4906763681 | | 1987 | 2,826.7673183146 | | 1986 | 2,705.5912263538 | | 1985 | 2,519.6180982426 | | 1984 | 2,537.2505691088 | | 1983 | 2,480.2074324261 | | 1982 | 2,329.8822960057 | | 1981 | 2,000.5338257365 | | 1980 | 1,804.3147505169 | | 1979 | 1,667.7005511054 | | 1978 | 1,419.883290518 | | 1977 | 1,344.1891553334 | | 1976 | 1,213.8286553476 | | 1975 | 1,088.2177422186 | | 1974 | 1,107.3824535635 | | 1973 | 1,076.4073904865 | | 1972 | 1,095.7216511637 | | 1971 | 990.87118674572 |
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