Quarter	Percent
1998-04-01	66.6
1999-04-01	66.4
2000-04-01	65.1
2001-04-01	68.2
2002-04-01	65.9
2003-04-01	67.4
2004-04-01	67.4
2005-04-01	67.6
2006-04-01	67.8
2007-04-01	69.3
2008-04-01	70.2
2009-04-01	70.2
2010-01-01	68.7
2010-04-01	68.8
2010-07-01	68.1
2010-10-01	68.8
2011-01-01	69.7
2011-04-01	69.9
2011-07-01	69.6
2011-10-01	70.4
2012-01-01	69.9
2012-04-01	70.7
2012-07-01	71.1
2012-10-01	70.7
2013-01-01	71.4
2013-04-01	72.1
2013-07-01	71.4
2013-10-01	71.6
2014-01-01	71.0
2014-04-01	71.9
2014-07-01	71.2
2014-10-01	72.4
2015-01-01	73.3
2015-04-01	72.7
2015-07-01	72.9
2015-10-01	74.0
2016-01-01	73.3
2016-04-01	74.7
2016-07-01	74.6
2016-10-01	74.7
2017-01-01	73.8
2017-04-01	75.1
2017-07-01	75.1
2017-10-01	76.2
2018-01-01	75.5
2018-04-01	76.5