Year Measure 1971 371.22502 1972 380.27814 1973 379.72171 1974 379.03572 1975 380.8561 1976 360.23564 1977 363.62143 1978 368.18213 1979 364.6681 1980 363.86601 1981 353.46276 1982 355.66744 1983 355.46043 1984 353.93651 1985 360.56179 1986 353.57291 1987 348.13924 1988 346.623 1989 337.99245 1990 333.69817 1991 327.53982 1992 324.14739 1993 320.35366 1994 316.29356 1995 312.7613 1996 352.92018 1997 355.23834 1998 340.20168 1999 344.56186 2000 288.76845 2001 297.95472 2002 310.03973 2003 317.1984 2004 321.35532 2005 313.10631 2006 358.89854 2007 379.22782 2008 376.85968 2009 384.44718 2010 397.13633 2011 396.77239 2012 399.68014 2013 406.25378 2014 416.79577