Year Percent 1995-01-01 0.36808200000000000 1996-01-01 0.37048600000000004 1997-01-01 0.29922400000000000 1998-01-01 0.26004800000000000 1999-01-01 0.25183300000000000 2000-01-01 0.19591000000000000 2001-01-01 0.19164200000000000 2002-01-01 0.23106700000000000 2003-01-01 0.26722300000000000 2004-01-01 0.25853899999999996 2005-01-01 0.28543200000000000 2006-01-01 0.29234299999999996 2007-01-01 0.31930200000000000 2008-01-01 0.33570100000000000 2009-01-01 0.31047900000000000 2010-01-01 0.35234499999999996 2011-01-01 0.36945000000000000 2012-01-01 0.43571200000000000 2013-01-01 0.47676800000000000 2014-01-01 0.49546200000000000 2015-01-01 0.56119700000000010 2016-01-01 0.58038100000000000