Year Percent 2005-01-01 0.34700000000000003 2006-01-01 1.62400000000000000 2007-01-01 2.47000000000000000 2008-01-01 2.81000000000000000 2009-01-01 3.43000000000000000 2010-01-01 3.66000000000000000 2011-01-01 3.83000000000000000 2012-01-01 4.34000000000000000 2013-01-01 5.01000000000000000 2014-01-01 5.12000000000000000 2015-01-01 5.57000000000000000 2016-01-01 6.00000000000000000