Quarter	Percent
2006-01-01	63.5
2006-04-01	67.6
2006-07-01	68.9
2006-10-01	67.5
2007-01-01	64.1
2007-04-01	67.8
2007-07-01	69
2007-10-01	66.4
2008-01-01	64
2008-04-01	68
2008-07-01	68.6
2008-10-01	65.6
2009-01-01	61.5
2009-04-01	64.7
2009-07-01	66.6
2009-10-01	65.4
2010-01-01	63.6
2010-04-01	67.7
2010-07-01	68.2
2010-10-01	67.1
2011-01-01	66.6
2011-04-01	69.8
2011-07-01	71.1
2011-10-01	69.4
2012-01-01	66.1
2012-04-01	69.9
2012-07-01	70.7
2012-10-01	70
2013-01-01	67.4
2013-04-01	70.5
2013-07-01	70.7
2013-10-01	69.2
2014-01-01	67.9
2014-04-01	70.9
2014-07-01	70.5
2014-10-01	68.8
2015-01-01	67.8
2015-04-01	70.7
2015-07-01	71.3
2015-10-01	69.5
2016-01-01	68.6
2016-04-01	71.3
2016-07-01	70.8
2016-10-01	69.5
2017-01-01	68.0
2017-04-01	71.3
2017-07-01	72.6
2017-10-01	71.0
2018-01-01	69.8
2018-04-01	71.7