Year Percent 2008-01-01 4.2828599999999994 2009-01-01 3.8966400000000000 2010-01-01 4.6789400000000000 2011-01-01 5.1884200000000000 2012-01-01 6.4075200000000000 2013-01-01 6.5056900000000000 2014-01-01 5.4956500000000000 2015-01-01 8.9828100000000000 2016-01-01 7.0218600000000000 2017-01-01 7.3080000000000000