Year Percent 2005-01-01 56.800 2006-01-01 53.675 2007-01-01 51.125 2008-01-01 49.475 2009-01-01 47.125 2010-01-01 45.400 2011-01-01 43.225 2012-01-01 41.850 2013-01-01 39.200 2014-01-01 37.100 2015-01-01 36.175 2016-01-01 34.100 2017-01-01 32.550