Year Percent 2006-01-01 19.325 2007-01-01 19.375 2008-01-01 19.775 2009-01-01 19.325 2010-01-01 20.250 2011-01-01 21.225 2012-01-01 20.725 2013-01-01 21.500 2014-01-01 22.050 2015-01-01 23.000 2016-01-01 23.200 2017-01-01 23.025