Year Measure 1971 313.85924 1972 317.8101 1973 320.4128 1974 327.98323 1975 333.51652 1976 346.94368 1977 350.43385 1978 358.03439 1979 364.43443 1980 366.15047 1981 298.00276 1982 301.84759 1983 303.41093 1984 299.24175 1985 294.76606 1986 224.2922 1987 226.3269 1988 229.25763 1989 228.85169 1990 219.79309 1991 215.14619 1992 219.07547 1993 207.65904 1994 187.16178 1995 216.52686 1996 243.99988 1997 252.46319 1998 248.1681 1999 247.10598 2000 235.14469 2001 236.28866 2002 261.37451 2003 247.08329 2004 250.87162 2005 367.69702 2006 372.72597 2007 384.51655 2008 383.51972 2009 383.23453 2010 379.67184 2011 387.37073 2012 395.77917 2013 392.84854 2014 392.80117