Quarter	Percent
1998-04-01	41.0
1998-10-01	39.9
1999-04-01	39.9
1999-10-01	40.0
2000-04-01	39.0
2000-10-01	40.5
2001-04-01	40.9
2001-10-01	42.1
2002-01-01	43.9
2002-04-01	47.5
2002-07-01	46.6
2002-10-01	47.6
2003-01-01	45.2
2003-04-01	45.4
2003-07-01	52.2
2003-10-01	46.7
2004-01-01	52.9
2004-04-01	49.8
2004-07-01	52.4
2004-10-01	51.2
2005-01-01	52.8
2005-04-01	50.6
2005-07-01	54.6
2005-10-01	54.3
2006-01-01	56.6
2006-04-01	56.0
2006-07-01	59.7
2006-10-01	56.8
2007-01-01	60.1
2007-04-01	59.8
2007-07-01	60.4
2007-10-01	62.6
2008-01-01	63.2
2008-04-01	63.5
2008-07-01	62.4
2008-10-01	63.0
2009-01-01	64.2
2009-04-01	66.0
2009-07-01	56.3
2009-10-01	57.1
2010-01-01	56.2
2010-04-01	59.9
2010-07-01	56.6
2010-10-01	54.8
2011-01-01	57.6
2011-04-01	60.2
2011-07-01	59.0
2011-10-01	61.0
2012-01-01	60.1
2012-04-01	63.0
2012-07-01	62.9
2012-10-01	61.4
2013-01-01	59.7
2013-04-01	62.6
2013-07-01	62.2
2013-10-01	60.6
2014-01-01	63.4
2014-04-01	62.8
2014-07-01	61.4
2014-10-01	62.5
2015-01-01	64.8
2015-04-01	64.6
2015-07-01	65.9
2015-10-01	66.6
2016-01-01	67.4
2016-04-01	68.6
2016-07-01	66.3
2016-10-01	68.1
2017-01-01	66.4
2017-04-01	68.1
2017-07-01	67.7
2017-10-01	69.2
2018-01-01	69.1
2018-04-01	71.7