Year Measure 1971 2228.68705 1972 2262.78655 1973 2378.25374 1974 2463.24405 1975 2665.45943 1976 2780.33176 1977 2954.26674 1978 3084.45204 1979 3200.49898 1980 3203.6101 1981 3185.50954 1982 3309.20643 1983 3370.13232 1984 3387.27422 1985 3419.76768 1986 3450.94172 1987 3411.07339 1988 3488.29275 1989 3426.94221 1990 3237.35265 1991 2536.64401 1992 2396.00727 1993 2590.01125 1994 2519.85915 1995 2746.66773 1996 2745.71 1997 2504.12268 1998 2425.94625 1999 2230.6603 2000 2277.36797 2001 2421.14536 2002 2410.96935 2003 2490.41667 2004 2440.69816 2005 2597.89617 2006 2691.46044 2007 2666.11145 2008 2648.86706 2009 2351.65505 2010 2416.70391 2011 2617.12787 2012 2513.35238 2013 2329.1228 2014 2477.6554