Quarter	Percent
2006-01-01	46.7
2006-04-01	49.6
2006-07-01	50.5
2006-10-01	49.2
2007-01-01	47.4
2007-04-01	50
2007-07-01	50.5
2007-10-01	48.4
2008-01-01	47.5
2008-04-01	50.5
2008-07-01	51.3
2008-10-01	50
2009-01-01	48.5
2009-04-01	51.1
2009-07-01	52.4
2009-10-01	51.1
2010-01-01	50.5
2010-04-01	52.6
2010-07-01	52.9
2010-10-01	51.7
2011-01-01	51.6
2011-04-01	53.9
2011-07-01	54.5
2011-10-01	52.8
2012-01-01	51.2
2012-04-01	53.9
2012-07-01	54.2
2012-10-01	54.1
2013-01-01	53
2013-04-01	55.3
2013-07-01	55.2
2013-10-01	54
2014-01-01	53.6
2014-04-01	55.8
2014-07-01	55.9
2014-10-01	55.1
2015-01-01	54.6
2015-04-01	56.5
2015-07-01	57.0
2015-10-01	56.0
2016-01-01	55.6
2016-04-01	57.4
2016-07-01	57.7
2016-10-01	57.1
2017-01-01	56.8
2017-04-01	58.2
2017-07-01	58.9
2017-10-01	58.0
2018-01-01	57.3
2018-04-01	58.5