Year Percent 2005-01-01 51.0348105161984 2006-01-01 53.2066388082511 2007-01-01 54.4178833966150 2008-01-01 55.7476708644682 2009-01-01 55.3539424077959 2010-01-01 58.0055375476203 2011-01-01 59.7411045611120 2012-01-01 62.7156658323421 2013-01-01 63.9461032918216 2014-01-01 64.2378700441240 2015-01-01 64.4919588633069 2016-01-01 63.8129078928909 2017-01-01 65.2660623365382