Year Percent 2008-01-01 7.100000000000000 2009-01-01 18.900000000000000 2010-01-01 20.930600000000000 2011-01-01 20.665500000000000 2012-01-01 19.389900000000000 2013-01-01 19.470800000000000 2014-01-01 12.392100000000000 2015-01-01 7.952539999999999 2016-01-01 6.718350000000000