Year Measure 1971 1310.88048 1972 1325.18809 1973 1320.44228 1974 1348.71664 1975 1367.70898 1976 1427.66165 1977 1482.91027 1978 1572.12622 1979 1660.56235 1980 1737.78232 1981 1758.34587 1982 1808.82884 1983 1846.06716 1984 1861.57107 1985 1907.01299 1986 1848.50039 1987 1755.23742 1988 1762.39089 1989 1730.63969 1990 1637.11386 1991 1538.33448 1992 1323.61123 1993 1198.58191 1994 1080.20481 1995 1005.61057 1996 874.1599 1997 824.46268 1998 762.48994 1999 809.81423 2000 859.90804 2001 880.58176 2002 838.4032 2003 850.8964 2004 863.7916 2005 892.5579 2006 895.62213 2007 756.3434 2008 828.8782 2009 814.23341 2010 768.79088 2011 566.22337 2012 573.55389 2013 434.17107 2014 474.23908