Year Percent 2008-01-01 1.5486500000000000 2009-01-01 1.8178900000000002 2010-01-01 3.6435199999999996 2011-01-01 3.1248500000000000 2012-01-01 9.5292600000000000 2013-01-01 10.0015000000000000 2014-01-01 9.8850699999999990 2015-01-01 9.8129400000000000 2016-01-01 15.0999000000000000