Year Percent 2006-01-01 2.99 2007-01-01 3.36 2008-01-01 2.83 2009-01-01 3.98 2010-01-01 3.90 2011-01-01 3.21 2012-01-01 3.53 2013-01-01 4.14 2014-01-01 4.38 2015-01-01 5.60