Quarter	Percent
2006-01-01	66.1
2006-04-01	64.4
2006-07-01	61.5
2006-10-01	62.9
2007-01-01	65.5
2007-04-01	63.7
2007-07-01	60.7
2007-10-01	64.1
2008-01-01	64.9
2008-04-01	63.6
2008-07-01	60.6
2008-10-01	62.3
2009-01-01	65.4
2009-04-01	63.1
2009-07-01	59
2009-10-01	62.7
2010-01-01	64.6
2010-04-01	63
2010-07-01	59.8
2010-10-01	63.1
2011-01-01	63.7
2011-04-01	61.7
2011-07-01	58.5
2011-10-01	62.2
2012-01-01	65.5
2012-04-01	62.8
2012-07-01	60.4
2012-10-01	61.9
2013-01-01	63.5
2013-04-01	60.9
2013-07-01	57.8
2013-10-01	62.6
2014-01-01	61.7
2014-04-01	58.7
2014-07-01	56.5
2014-10-01	60
2015-01-01	61.0
2015-04-01	58.7
2015-07-01	54.2
2015-10-01	59.0
2016-01-01	60.3
2016-04-01	57.3
2016-07-01	55.0
2016-10-01	58.0
2017-01-01	59.3
2017-04-01	56.8
2017-07-01	53.5
2017-10-01	57.6
2018-01-01	59.0
2018-04-01	56.9