Year Percent 2002-01-01 49.900200000000000 2003-01-01 42.107200000000000 2004-01-01 34.344400000000000 2005-01-01 30.425400000000000 2006-01-01 25.807200000000000 2007-01-01 24.089600000000000 2008-01-01 25.958600000000000 2009-01-01 31.004100000000000 2010-01-01 34.336999999999996 2011-01-01 36.207300000000000 2012-01-01 38.932100000000000 2013-01-01 39.281800000000000 2014-01-01 34.780100000000000 2015-01-01 34.307500000000000 2016-01-01 33.473700000000000 2017-01-01 32.464000000000000