Year Percent 2005-01-01 50.1 2006-01-01 50.5 2007-01-01 50.8 2008-01-01 50.8 2009-01-01 49.9 2010-01-01 49.6 2011-01-01 49.6 2012-01-01 49.7 2013-01-01 50.0 2014-01-01 50.3 2015-01-01 50.6 2016-01-01 51.1