Year Percent 2006-01-01 0.37 2007-01-01 0.84 2008-01-01 1.21 2009-01-01 2.11 2010-01-01 2.86 2011-01-01 3.48 2012-01-01 4.57 2013-01-01 5.40 2014-01-01 6.36 2015-01-01 7.29 2016-01-01 8.19