Year Percent 2005-01-01 49.375 2006-01-01 50.325 2007-01-01 51.275 2008-01-01 51.900 2009-01-01 51.500 2010-01-01 51.325 2011-01-01 51.500 2012-01-01 51.575 2013-01-01 51.625 2014-01-01 52.175 2015-01-01 52.775 2016-01-01 53.575 2017-01-01 54.375