Year Measure 1971 6394.72203 1972 5971.47346 1973 8495.33456 1974 9009.06272 1975 8000.6453 1976 9584.32363 1977 8188.76227 1978 7844.32086 1979 8814.10627 1980 7794.79449 1981 8295.06308 1982 9071.02474 1983 8502.8881 1984 8833.12256 1985 9921.6532 1986 10261.44107 1987 9523.90901 1988 10493.49745 1989 10248.37349 1990 10555.27079 1991 10108.35385 1992 10837.7268 1993 11142.36134 1994 11555.53615 1995 11408.51944 1996 11109.67083 1997 12181.22132 1998 12406.71042 1999 11851.5266 2000 11988.72127 2001 11738.14599 2002 11548.54941 2003 11566.50028 2004 10894.96269 2005 11675.40667 2006 11604.24931 2007 11234.22155 2008 11318.77551 2009 10339.60097 2010 10207.85148 2011 9911.79634 2012 9657.5687 2013 10416.78989 2014 10593.99714