Year Percent 2011-01-01 3.5413900000000003 2012-01-01 3.5413900000000003 2013-01-01 3.5413900000000003 2014-01-01 6.8337400000000000 2015-01-01 6.8337400000000000 2016-01-01 6.8337400000000000 2017-01-01 8.7541200000000000