Year Percent 1995-01-01 59.3946465350000 1996-01-01 58.5255662175000 1997-01-01 57.3899137600000 1998-01-01 56.0794334825000 1999-01-01 55.5743727600000 2000-01-01 55.6226963525000 2001-01-01 55.2788255650000 2002-01-01 54.1478142000000 2003-01-01 54.0050388875000 2004-01-01 54.8450037025000 2005-01-01 55.4910155200000 2006-01-01 56.2565039050000 2007-01-01 57.5753511975000 2008-01-01 58.4116132100000 2009-01-01 57.0807052675000 2010-01-01 57.9560707375000 2011-01-01 58.8476778975000 2012-01-01 64.6250000000000 2013-01-01 65.1083333333333 2014-01-01 65.3833333333334 2015-01-01 65.7416666666667 2016-01-01 65.8833333333334 2017-01-01 66.1333333333333