Quarter	Percent
1998-04-01	64.6
1999-04-01	64.6
2000-04-01	64.1
2001-04-01	65.5
2002-04-01	66
2003-04-01	66.2
2004-04-01	65.9
2005-04-01	66.3
2006-04-01	66.9
2007-04-01	66.9
2008-04-01	68.5
2009-04-01	68.9
2010-01-01	67.3
2010-04-01	66.9
2010-07-01	67.3
2010-10-01	67.1
2011-01-01	67.8
2011-04-01	67.6
2011-07-01	67.7
2011-10-01	68.5
2012-01-01	68.2
2012-04-01	67.9
2012-07-01	68.5
2012-10-01	68.1
2013-01-01	68.4
2013-04-01	68.3
2013-07-01	68.6
2013-10-01	68.9
2014-01-01	68.8
2014-04-01	69.0
2014-07-01	69.3
2014-10-01	70.5
2015-01-01	69.9
2015-04-01	69.5
2015-07-01	69.5
2015-10-01	70.2
2016-01-01	70.9
2016-04-01	70.3
2016-07-01	70.4
2016-10-01	70.7
2017-01-01	70.5
2017-04-01	69.9
2017-07-01	70.2
2017-10-01	70.5
2018-01-01	70.7
2018-04-01	70.5