Quarter	Percent
1998-04-01	61.9
1999-04-01	62.3
2000-04-01	62.1
2001-04-01	63.2
2002-04-01	64
2003-04-01	63.3
2004-04-01	62.8
2005-04-01	62.9
2006-04-01	63.7
2007-04-01	63.9
2008-04-01	65.7
2009-04-01	65.7
2010-01-01	63.6
2010-04-01	63.5
2010-07-01	63.5
2010-10-01	64.0
2011-01-01	64.4
2011-04-01	64.9
2011-07-01	64.1
2011-10-01	65.1
2012-01-01	65.0
2012-04-01	64.8
2012-07-01	65.2
2012-10-01	64.8
2013-01-01	64.8
2013-04-01	65.0
2013-07-01	65.2
2013-10-01	65.7
2014-01-01	65.1
2014-04-01	65.7
2014-07-01	65.6
2014-10-01	67.3
2015-01-01	66.8
2015-04-01	66.3
2015-07-01	65.7
2015-10-01	66.6
2016-01-01	67.2
2016-04-01	66.9
2016-07-01	66.6
2016-10-01	67.2
2017-01-01	66.9
2017-04-01	66.5
2017-07-01	66.4
2017-10-01	67.0
2018-01-01	66.8
2018-04-01	66.8