Year Measure 1971 268.12342 1972 268.08184 1973 269.37777 1974 273.50078 1975 276.70765 1976 281.26765 1977 282.7815 1978 280.21943 1979 286.40982 1980 287.05476 1981 294.67555 1982 299.05247 1983 301.70057 1984 307.10324 1985 315.98307 1986 319.98203 1987 325.02884 1988 335.45032 1989 343.9333 1990 351.34077 1991 358.66187 1992 364.39514 1993 365.83442 1994 372.56455 1995 386.47099 1996 390.80777 1997 398.77052 1998 400.87884 1999 416.37397 2000 418.68428 2001 417.38199 2002 422.62733 2003 425.63279 2004 441.06478 2005 451.13831 2006 467.54576 2007 486.55048 2008 503.03558 2009 546.17673 2010 563.1593 2011 579.40874 2012 600.44323 2013 606.87428 2014 637.42863