Year Percent 1998-01-01 0.09097300000000000 1999-01-01 0.07869700000000000 2000-01-01 0.07895400000000000 2001-01-01 0.09022600000000000 2002-01-01 0.07245599999999999 2003-01-01 0.07416500000000000 2004-01-01 0.14184300000000000 2005-01-01 0.16344200000000000 2006-01-01 0.15192700000000000 2007-01-01 0.14975000000000000 2008-01-01 0.16205200000000000 2009-01-01 0.16248500000000000 2010-01-01 0.14851900000000000 2011-01-01 0.14149700000000000 2012-01-01 0.13967000000000002 2013-01-01 0.13066400000000000 2014-01-01 0.12778800000000000 2015-01-01 0.12500700000000000 2016-01-01 0.12449900000000000 2017-01-01 0.12795399999999998