Year Measure 1971 361.92204 1972 291.09852 1973 292.48388 1974 363.4116 1975 405.12644 1976 443.55919 1977 476.80131 1978 504.00064 1979 631.70378 1980 499.97772 1981 576.2144 1982 666.84146 1983 737.83388 1984 820.05021 1985 735.49776 1986 730.99793 1987 787.40001 1988 790.60687 1989 769.83834 1990 840.84551 1991 889.73571 1992 827.21875 1993 808.27315 1994 820.03903 1995 843.33308 1996 865.67532 1997 913.80413 1998 990.54903 1999 960.70646 2000 940.88587 2001 944.75693 2002 963.24177 2003 949.88294 2004 970.91798 2005 1136.49943 2006 1143.50908 2007 1153.21198 2008 1136.53336 2009 1032.00967 2010 1030.49617 2011 953.40964 2012 726.9748 2013 587.43643 2014 562.5354