Year Percent 2011-01-01 3.1829800000000000 2012-01-01 3.1829800000000000 2013-01-01 3.1829800000000000 2014-01-01 7.9951300000000005 2015-01-01 7.9951300000000005 2016-01-01 7.9951300000000005 2017-01-01 8.5057200000000000