Year Percent 2005-01-01 41.6 2006-01-01 42.9 2007-01-01 43.7 2008-01-01 44.3 2009-01-01 44.7 2010-01-01 45.4 2011-01-01 46.1 2012-01-01 47.1 2013-01-01 48.1 2014-01-01 49.1 2015-01-01 50.0 2016-01-01 51.1