Year Percent 2005-01-01 54.8 2006-01-01 55.9 2007-01-01 56.7 2008-01-01 57.3 2009-01-01 56.9 2010-01-01 57.0 2011-01-01 57.5 2012-01-01 58.4 2013-01-01 59.5 2014-01-01 60.6 2015-01-01 61.4 2016-01-01 62.4