Quarter	Percent
1998-04-01	51.4
1999-04-01	51.1
2000-04-01	50.1
2001-04-01	53.6
2002-04-01	52.3
2003-04-01	54.1
2004-04-01	54.1
2005-04-01	55.6
2006-04-01	56.6
2007-04-01	58.1
2008-04-01	60
2009-04-01	59.6
2010-01-01	57.7
2010-04-01	57.4
2010-07-01	55.8
2010-10-01	57.0
2011-01-01	58.1
2011-04-01	58.6
2011-07-01	57.8
2011-10-01	59.1
2012-01-01	59.2
2012-04-01	60.5
2012-07-01	60.3
2012-10-01	59.0
2013-01-01	60.9
2013-04-01	62.1
2013-07-01	61.4
2013-10-01	60.8
2014-01-01	61.0
2014-04-01	62.8
2014-07-01	62.2
2014-10-01	62.3
2015-01-01	63.0
2015-04-01	63.6
2015-07-01	64.0
2015-10-01	65.1
2016-01-01	65.4
2016-04-01	66.2
2016-07-01	65.5
2016-10-01	66.0
2017-01-01	64.5
2017-04-01	65.8
2017-07-01	65.9
2017-10-01	66.8
2018-01-01	66.6
2018-04-01	66.7