Year Measure 1971 857.55694 1972 872.98574 1973 845.72838 1974 832.35395 1975 863.96268 1976 873.23421 1977 868.79271 1978 883.8665 1979 937.47909 1980 906.55324 1981 867.98015 1982 766.14284 1983 704.81691 1984 672.81752 1985 663.30578 1986 680.07758 1987 718.44768 1988 765.34937 1989 780.31935 1990 723.84597 1991 779.41604 1992 855.12425 1993 792.1618 1994 751.14778 1995 797.56692 1996 872.90377 1997 880.63473 1998 900.58831 1999 977.90542 2000 930.94276 2001 814.99581 2002 762.69746 2003 758.64504 2004 863.10113 2005 889.20686 2006 955.4581 2007 947.84116 2008 1239.44051 2009 1228.18641 2010 1211.18327 2011 1305.02265 2012 1365.20737 2013 1350.43464 2014 1378.27361