Year Percent 2011-01-01 6.4168199999999995 2012-01-01 6.4168199999999995 2013-01-01 6.4168199999999995 2014-01-01 6.5958900000000000 2015-01-01 6.5958900000000000 2016-01-01 6.5958900000000000 2017-01-01 9.0171000000000000