Year Percent 2006-01-01 0.58 2007-01-01 0.60 2008-01-01 0.68 2009-01-01 3.75 2010-01-01 3.98 2011-01-01 4.48 2012-01-01 4.83 2013-01-01 4.79 2014-01-01 5.15 2015-01-01 5.86