Year Percent 1998-01-01 0.32539900000000000 1999-01-01 0.33906200000000000 2000-01-01 0.28921500000000000 2001-01-01 0.32590100000000000 2002-01-01 0.35865700000000000 2003-01-01 0.31083500000000000 2004-01-01 0.30645200000000000 2005-01-01 0.28056600000000000 2006-01-01 0.26493800000000000 2007-01-01 0.30615000000000000 2008-01-01 0.28744200000000003 2009-01-01 0.31367700000000000 2010-01-01 0.32789400000000000 2011-01-01 0.37563900000000000 2012-01-01 0.43147299999999994 2013-01-01 0.43688999999999995 2014-01-01 0.43724700000000005 2015-01-01 0.43973300000000000 2016-01-01 0.41699300000000000