Year Measure 1971 313.13453 1972 347.30774 1973 374.97742 1974 400.2954 1975 429.93269 1976 466.68136 1977 530.86084 1978 560.53961 1979 618.26714 1980 658.78516 1981 688.84323 1982 728.64815 1983 768.22284 1984 816.23921 1985 842.74946 1986 883.9488 1987 923.98791 1988 996.85287 1989 1075.73171 1990 1156.81498 1991 1265.60664 1992 1418.41853 1993 1532.90847 1994 1784.26923 1995 2003.79623 1996 2187.28525 1997 2471.60662 1998 2525.47498 1999 2648.71303 2000 2748.08407 2001 2759.53655 2002 2821.66756 2003 2915.86804 2004 2986.32218 2005 2877.23096 2006 3072.41942 2007 3284.51548 2008 3301.23464 2009 3960.60435 2010 4159.63994 2011 4104.88823 2012 4323.34688 2013 4484.16998 2014 4596.33194