Quarter	Percent
2005-01-01	61.1
2005-04-01	61.1
2005-07-01	60.9
2005-10-01	60.7
2006-01-01	60.2
2006-04-01	60.2
2006-07-01	60.3
2006-10-01	59.3
2007-01-01	60.0
2007-04-01	60.9
2007-07-01	61.4
2007-10-01	59.8
2008-01-01	60.0
2008-04-01	60.5
2008-07-01	61.9
2008-10-01	61.8
2009-01-01	61.4
2009-04-01	62.1
2009-07-01	62.6
2009-10-01	61.9
2010-01-01	61.5
2010-04-01	62.0
2010-07-01	63.1
2010-10-01	63.5
2011-01-01	63.3
2011-04-01	64.0
2011-07-01	63.7
2011-10-01	63.2
2012-01-01	63.5
2012-04-01	64.4
2012-07-01	64.7
2012-10-01	64.0
2013-01-01	64.0
2013-04-01	64.7
2013-07-01	64.8
2013-10-01	64.9
2014-01-01	65.6
2014-04-01	65.7
2014-07-01	66.3
2014-10-01	65.7
2015-01-01	65.6
2015-04-01	66.3
2015-07-01	66.5
2015-10-01	66.7
2016-01-01	66.9
2016-04-01	67.9
2016-07-01	67.9
2016-10-01	67.7
2017-01-01	67.7
2017-04-01	68.4
2017-07-01	68.1
2017-10-01	68.1
2018-01-01	68.3
2018-04-01	68.9