Year Measure 1971 391.52359 1972 404.47441 1973 424.8396 1974 447.15034 1975 521.12856 1976 624.53937 1977 625.54464 1978 690.787 1979 798.81517 1980 712.14418 1981 684.66419 1982 690.29282 1983 810.50128 1984 835.65948 1985 945.02707 1986 998.77212 1987 969.96314 1988 1144.17042 1989 1231.89425 1990 1147.36764 1991 889.26503 1992 1284.36054 1993 1623.02555 1994 1783.99845 1995 1661.88276 1996 1613.00099 1997 1860.04355 1998 1286.27933 1999 964.13465 2000 1101.75243 2001 1196.87321 2002 1106.75424 2003 989.64851 2004 991.81331 2005 978.59479 2006 900.38144 2007 893.82987 2008 944.21227 2009 1101.9858 2010 1219.37245 2011 1293.56367 2012 1399.27499 2013 1456.6628 2014 1413.49626