Year Measure 1971 990.56307 1972 1133.75435 1973 1218.68461 1974 1043.06293 1975 1029.61886 1976 1139.10459 1977 1217.07877 1978 1284.81057 1979 1358.80155 1980 1415.21959 1981 1436.50433 1982 1536.78896 1983 1655.43592 1984 1684.06388 1985 1766.41035 1986 1872.69861 1987 1950.5654 1988 2091.03043 1989 2295.47137 1990 2430.16694 1991 2481.07272 1992 2837.83969 1993 3004.57648 1994 3058.14051 1995 2784.71423 1996 2816.50472 1997 2866.94674 1998 3097.81843 1999 3178.01415 2000 3373.31414 2001 3455.23502 2002 3703.30185 2003 3918.22159 2004 3946.91264 2005 4099.61291 2006 4238.12707 2007 4377.12464 2008 4554.51971 2009 4577.09667 2010 4585.62637 2011 4239.73294 2012 4035.02188 2013 3587.73875 2014 3624.89575