Year Percent 2005-01-01 51.7 2006-01-01 52.7 2007-01-01 53.5 2008-01-01 54.0 2009-01-01 53.7 2010-01-01 54.0 2011-01-01 54.5 2012-01-01 55.5 2013-01-01 56.3 2014-01-01 57.3 2015-01-01 58.1 2016-01-01 59.2