Year Percent 2005-01-01 38.2106965640422 2006-01-01 38.9098935733627 2007-01-01 38.9928813872953 2008-01-01 41.4801071532995 2009-01-01 39.6950962362543 2010-01-01 43.8388795677595 2011-01-01 44.2518529637356 2012-01-01 42.0730245658773 2013-01-01 41.0537500390090 2014-01-01 40.8240668703029 2015-01-01 40.8068904591153 2016-01-01 39.2008986108931 2017-01-01 37.7193588665725