Year Percent 2005-01-01 41.3263 2006-01-01 37.5725 2007-01-01 37.5555 2008-01-01 36.2981 2009-01-01 37.4452 2010-01-01 35.7152 2011-01-01 33.7047 2012-01-01 36.8731 2013-01-01 36.6563 2014-01-01 32.7696 2015-01-01 35.6093 2016-01-01 36.9395 2017-01-01 38.7817