Year Percent 2000-01-01 56.600 2001-01-01 57.000 2002-01-01 57.450 2003-01-01 58.950 2004-01-01 58.475 2005-01-01 58.975 2006-01-01 63.450 2007-01-01 64.650 2008-01-01 64.800 2009-01-01 56.625 2010-01-01 54.025 2011-01-01 59.125 2012-01-01 60.900 2013-01-01 62.150 2014-01-01 63.475 2015-01-01 65.150 2016-01-01 65.275 2017-01-01 66.975