Year Percent 2006-01-01 0.17333900000000002 2007-01-01 0.19411700000000000 2008-01-01 0.18244500000000000 2009-01-01 0.20202300000000000 2010-01-01 0.25949000000000000 2011-01-01 0.28880100000000003 2012-01-01 0.28682100000000000 2013-01-01 0.32692400000000000 2014-01-01 0.35192399999999996 2015-01-01 0.38057100000000000 2016-01-01 0.56875700000000000