Year Percent 2006-01-01 41.625 2007-01-01 40.575 2008-01-01 40.950 2009-01-01 41.075 2010-01-01 42.700 2011-01-01 45.400 2012-01-01 46.325 2013-01-01 45.175 2014-01-01 45.625 2015-01-01 46.275 2016-01-01 49.150 2017-01-01 50.550