Quarter	Percent
2006-01-01	73.4
2006-04-01	69.8
2006-07-01	69.5
2006-10-01	72.5
2007-01-01	73.4
2007-04-01	69.8
2007-07-01	71.3
2007-10-01	72.9
2008-01-01	74
2008-04-01	69.5
2008-07-01	69.5
2008-10-01	72.1
2009-01-01	72.3
2009-04-01	69.6
2009-07-01	69.3
2009-10-01	69.2
2010-01-01	70
2010-04-01	67.6
2010-07-01	68.4
2010-10-01	69.5
2011-01-01	69
2011-04-01	66.3
2011-07-01	66
2011-10-01	67.6
2012-01-01	69
2012-04-01	66
2012-07-01	66.3
2012-10-01	66.2
2013-01-01	68.5
2013-04-01	65.8
2013-07-01	66.4
2013-10-01	67.3
2014-01-01	68.9
2014-04-01	65.3
2014-07-01	65.9
2014-10-01	66.3
2015-01-01	67.7
2015-04-01	64.6
2015-07-01	65.5
2015-10-01	65.8
2016-01-01	65.3
2016-04-01	63.3
2016-07-01	64.3
2016-10-01	64.5
2017-01-01	64.5
2017-04-01	63.4
2017-07-01	62.5
2017-10-01	62.3
2018-01-01	63.5
2018-04-01	61.6