Year Percent 2006-01-01 27.675 2007-01-01 27.175 2008-01-01 27.500 2009-01-01 28.200 2010-01-01 29.550 2011-01-01 31.325 2012-01-01 31.850 2013-01-01 31.475 2014-01-01 31.400 2015-01-01 31.800 2016-01-01 33.425 2017-01-01 34.425