Year Measure 1971 1016.46847 1972 1000.90826 1973 1024.52749 1974 1003.87388 1975 967.51186 1976 990.11493 1977 932.83125 1978 899.04615 1979 886.81237 1980 906.25309 1981 885.97607 1982 859.26893 1983 847.2847 1984 829.48576 1985 855.26462 1986 872.39852 1987 920.05936 1988 901.41616 1989 893.87965 1990 913.00813 1991 943.71842 1992 952.61273 1993 892.72977 1994 869.48972 1995 869.332 1996 850.80145 1997 828.5453 1998 834.75943 1999 877.59157 2000 818.87952 2001 807.16981 2002 784.47681 2003 742.31356 2004 717.12002 2005 743.13356 2006 750.19633 2007 723.93292 2008 661.31478 2009 661.58666 2010 671.49894 2011 712.58317 2012 734.83664 2013 749.66711