Year Percent 2007-01-01 1.90 2008-01-01 2.12 2009-01-01 2.54 2010-01-01 2.62 2011-01-01 2.67 2012-01-01 32.36 2013-01-01 30.72 2014-01-01 32.49 2015-01-01 45.14