Year Measure 1990 1004.54641 1991 938.90049 1992 752.89789 1993 579.91614 1994 438.05979 1995 385.98268 1996 367.25025 1997 360.7867 1998 373.78969 1999 366.05261 2000 345.65495 2001 335.19205 2002 329.94369 2003 329.6446 2004 349.27492 2005 341.41186 2006 344.66615 2007 360.5533 2008 335.6932 2009 285.34158 2010 284.75168 2011 279.19719 2012 293.52743 2013 318.07847 2014 335.38545