Year Percent 2000-01-01 52.700 2001-01-01 52.700 2002-01-01 53.275 2003-01-01 54.925 2004-01-01 54.000 2005-01-01 56.525 2006-01-01 57.250 2007-01-01 58.975 2008-01-01 64.725 2009-01-01 59.275 2010-01-01 51.925 2011-01-01 57.150 2012-01-01 59.150 2013-01-01 61.425 2014-01-01 65.150 2015-01-01 63.075 2016-01-01 63.750 2017-01-01 66.575