Year Measure 1971 465.32105 1972 484.99313 1973 500.10901 1974 499.32321 1975 544.92788 1976 615.58445 1977 621.96499 1978 645.49715 1979 617.85598 1980 549.90543 1981 584.64236 1982 594.80122 1983 563.70701 1984 567.61672 1985 532.98469 1986 456.85729 1987 503.29955 1988 463.60769 1989 469.12972 1990 469.78468 1991 509.57514 1992 524.65691 1993 544.84289 1994 569.6713 1995 598.60117 1996 565.95301 1997 620.23358 1998 632.3921 1999 650.96125 2000 676.10563 2001 702.75681 2002 712.34952 2003 739.7294 2004 730.13286 2005 747.65669 2006 781.65643 2007 736.18384 2008 736.077 2009 686.3967 2010 689.42998 2011 692.95057 2012 679.14402 2013 638.13091 2014 647.30961