Quarter	Percent
1998-04-01	52.4
1999-04-01	52.5
2000-04-01	51.3
2001-04-01	54.5
2002-04-01	53.2
2003-04-01	55.4
2004-04-01	56
2005-04-01	57.7
2006-04-01	58.6
2007-04-01	60.3
2008-04-01	61.6
2009-04-01	61
2010-01-01	59.7
2010-04-01	59.3
2010-07-01	57.9
2010-10-01	59.1
2011-01-01	60.5
2011-04-01	60.8
2011-07-01	59.8
2011-10-01	61.3
2012-01-01	61.4
2012-04-01	62.6
2012-07-01	62.0
2012-10-01	61.4
2013-01-01	63.1
2013-04-01	64.4
2013-07-01	63.1
2013-10-01	62.4
2014-01-01	63.0
2014-04-01	65.2
2014-07-01	64.1
2014-10-01	64.2
2015-01-01	65.2
2015-04-01	65.7
2015-07-01	66.7
2015-10-01	67.4
2016-01-01	67.7
2016-04-01	68.5
2016-07-01	67.5
2016-10-01	68.0
2017-01-01	66.8
2017-04-01	67.9
2017-07-01	68.2
2017-10-01	69.2
2018-01-01	69.2
2018-04-01	69.1