Year Percent 2005-01-01 51.575 2006-01-01 52.600 2007-01-01 53.700 2008-01-01 54.775 2009-01-01 54.625 2010-01-01 54.475 2011-01-01 54.900 2012-01-01 56.225 2013-01-01 57.375 2014-01-01 58.800 2015-01-01 60.100 2016-01-01 61.950 2017-01-01 63.675