Quarter	Percent
2005-01-01	41.6
2005-04-01	46.1
2005-07-01	47.0
2005-10-01	44.6
2006-01-01	48.4
2006-04-01	49.0
2006-07-01	46.3
2006-10-01	46.8
2007-01-01	49.9
2007-04-01	49.7
2007-07-01	50.2
2007-10-01	46.8
2008-01-01	47.9
2008-04-01	49.9
2008-07-01	51.6
2008-10-01	49.3
2009-01-01	51.4
2009-04-01	53.1
2009-07-01	52.7
2009-10-01	52.6
2010-01-01	51.6
2010-04-01	51.8
2010-07-01	51.0
2010-10-01	52.6
2011-01-01	53.1
2011-04-01	53.6
2011-07-01	52.9
2011-10-01	52.6
2012-01-01	53.7
2012-04-01	54.2
2012-07-01	54.9
2012-10-01	54.0
2013-01-01	55.7
2013-04-01	55.7
2013-07-01	55.7
2013-10-01	57.4
2014-01-01	58.2
2014-04-01	57.6
2014-07-01	59.9
2014-10-01	60.1
2015-01-01	61.9
2015-04-01	63.2
2015-07-01	62.9
2015-10-01	65.4
2016-01-01	67.0
2016-04-01	66.5
2016-07-01	66.5
2016-10-01	68.8
2017-01-01	69.5
2017-04-01	69.8
2017-07-01	68.6
2017-10-01	70.6
2018-01-01	71.6
2018-04-01	71.0