Year Percent 2006-01-01 36.45 2007-01-01 22.20 2008-01-01 32.65 2009-01-01 40.15 2010-01-01 49.00 2011-01-01 20.90 2012-01-01 25.30 2013-01-01 34.10 2014-01-01 21.50 2015-01-01 32.80