Quarter	Percent
1998-04-01	64.5
1999-04-01	64.7
2000-04-01	63.3
2001-04-01	67.1
2002-04-01	64.6
2003-04-01	65.8
2004-04-01	65.2
2005-04-01	65.1
2006-04-01	65.7
2007-04-01	67.2
2008-04-01	68.4
2009-04-01	68.3
2010-01-01	66.1
2010-04-01	66.5
2010-07-01	65.7
2010-10-01	66.6
2011-01-01	67.1
2011-04-01	67.4
2011-07-01	67.4
2011-10-01	67.8
2012-01-01	67.4
2012-04-01	68.4
2012-07-01	69.0
2012-10-01	68.1
2013-01-01	68.9
2013-04-01	69.5
2013-07-01	69.3
2013-10-01	69.3
2014-01-01	68.7
2014-04-01	69.3
2014-07-01	69.0
2014-10-01	69.9
2015-01-01	70.4
2015-04-01	70.2
2015-07-01	69.7
2015-10-01	70.9
2016-01-01	70.5
2016-04-01	71.6
2016-07-01	71.9
2016-10-01	71.9
2017-01-01	70.9
2017-04-01	72.3
2017-07-01	72.4
2017-10-01	73.1
2018-01-01	72.2
2018-04-01	73.4