Year Measure 1971 186.12968 1972 213.66023 1973 259.35727 1974 298.41557 1975 383.24437 1976 488.12089 1977 646.7543 1978 621.82252 1979 725.19476 1980 721.37901 1981 789.2058 1982 860.65814 1983 918.66335 1984 973.90986 1985 1026.40091 1986 1029.27574 1987 1006.99881 1988 995.05468 1989 832.05449 1990 916.81264 1991 904.70169 1992 883.86704 1993 865.72616 1994 765.116 1995 770.62102 1996 848.299 1997 856.14939 1998 917.84321 1999 901.91901 2000 878.06083 2001 896.80486 2002 921.65614 2003 930.62058 2004 908.9543 2005 907.97263 2006 935.74116 2007 958.90862 2008 970.44346 2009 932.09155 2010 948.04934 2011 959.87216 2012 984.73546 2013 1079.64085 2014 1172.88732