Year Measure 1971 235.75987 1972 260.45869 1973 321.8873 1974 309.39009 1975 314.46812 1976 329.21826 1977 328.1991 1978 328.53186 1979 345.38322 1980 373.5049 1981 337.32527 1982 338.1368 1983 362.4524 1984 341.32104 1985 350.12376 1986 311.37513 1987 319.36735 1988 343.12057 1989 360.57835 1990 360.74184 1991 353.85837 1992 334.98021 1993 335.19756 1994 377.175 1995 398.52101 1996 428.28086 1997 462.05583 1998 478.34024 1999 467.3822 2000 499.34885 2001 518.88328 2002 522.38382 2003 555.56925 2004 575.4708 2005 576.64955 2006 568.25339 2007 582.38288 2008 585.56373 2009 590.12667 2010 639.5408 2011 645.43797 2012 666.49363 2013 685.66503 2014 699.20507