Year Percent 2005-01-01 39.2678838976065 2006-01-01 40.0099787273480 2007-01-01 40.2836538207092 2008-01-01 40.3794829080868 2009-01-01 40.2603956111750 2010-01-01 40.3544599645732 2011-01-01 40.7457544687158 2012-01-01 41.6094496995955 2013-01-01 41.5772205000627 2014-01-01 41.2772688055326 2015-01-01 41.8238763005714 2016-01-01 42.1947896764657 2017-01-01 42.3738653948305