Quarter	Percent
2005-01-01	51.3
2005-04-01	54.4
2005-07-01	53.9
2005-10-01	53.4
2006-01-01	54.0
2006-04-01	53.5
2006-07-01	52.3
2006-10-01	51.8
2007-01-01	55.2
2007-04-01	55.8
2007-07-01	57.0
2007-10-01	53.1
2008-01-01	53.8
2008-04-01	55.7
2008-07-01	56.0
2008-10-01	56.2
2009-01-01	57.4
2009-04-01	58.2
2009-07-01	57.5
2009-10-01	55.6
2010-01-01	56.2
2010-04-01	57.2
2010-07-01	55.9
2010-10-01	56.6
2011-01-01	57.6
2011-04-01	58.0
2011-07-01	58.1
2011-10-01	58.1
2012-01-01	58.2
2012-04-01	58.2
2012-07-01	59.9
2012-10-01	58.5
2013-01-01	59.3
2013-04-01	59.3
2013-07-01	59.8
2013-10-01	62.0
2014-01-01	62.9
2014-04-01	61.8
2014-07-01	63.7
2014-10-01	63.6
2015-01-01	64.4
2015-04-01	66.5
2015-07-01	66.3
2015-10-01	67.5
2016-01-01	69.1
2016-04-01	70.3
2016-07-01	70.2
2016-10-01	70.5
2017-01-01	70.6
2017-04-01	71.3
2017-07-01	70.6
2017-10-01	72.6
2018-01-01	73.6
2018-04-01	73.4