Year Measure 1971 532.02843 1972 568.4032 1973 593.44675 1974 591.03264 1975 739.34509 1976 908.67455 1977 1067.81416 1978 1098.48317 1979 1065.7674 1980 1142.96536 1981 1123.96811 1982 1096.87323 1983 1070.69016 1984 1018.10029 1985 796.35397 1986 1420.61479 1987 1161.95168 1988 1005.93953 1989 1021.3935 1990 552.25218 1991 418.45359 1992 453.64407 1993 536.36383 1994 596.40796 1995 663.784 1996 904.34664 1997 694.6648 1998 734.84991 1999 1414.70378 2000 1449.64741 2001 1351.2308 2002 1578.16592 2003 1469.26454 2004 1797.52549 2005 1722.07285 2006 1218.36015 2007 1213.12437 2008 1617.74416 2009 1835.68407 2010 1943.34335 2011 2205.70392 2012 2118.32778 2013 2533.25283 2014 2309.3665