Year Percent 2009-01-01 17.1000 2010-01-01 15.9048 2011-01-01 17.8861 2012-01-01 18.1858 2013-01-01 20.3784 2014-01-01 19.5831 2015-01-01 18.7464 2016-01-01 20.2147