Year Percent 2003-01-01 37.000 2004-01-01 37.825 2005-01-01 38.550 2006-01-01 38.125 2007-01-01 38.225 2008-01-01 38.175 2009-01-01 38.925 2010-01-01 39.725 2011-01-01 41.375 2012-01-01 44.475 2013-01-01 45.600 2014-01-01 46.925 2015-01-01 48.725 2016-01-01 49.800 2017-01-01 51.275