Year Percent 2007-01-01 0.04 2008-01-01 0.04 2009-01-01 0.02 2010-01-01 0.01 2011-01-01 8.76 2012-01-01 5.80 2013-01-01 3.55 2014-01-01 2.46 2015-01-01 3.47