Quarter	Percent
1998-04-01	59.8
1998-10-01	59.7
1999-04-01	58.8
1999-10-01	58.4
2000-04-01	57.4
2000-10-01	57.2
2001-04-01	58.1
2001-10-01	58.3
2002-01-01	57.9
2002-04-01	59.6
2002-07-01	61.3
2002-10-01	61.0
2003-01-01	60.3
2003-04-01	60.3
2003-07-01	62.0
2003-10-01	60.4
2004-01-01	60.5
2004-04-01	60.5
2004-07-01	61.9
2004-10-01	61.2
2005-01-01	60.7
2005-04-01	62.1
2005-07-01	62.7
2005-10-01	63.1
2006-01-01	63.5
2006-04-01	65.6
2006-07-01	67.8
2006-10-01	66.7
2007-01-01	65.8
2007-04-01	67.4
2007-07-01	69.4
2007-10-01	69.9
2008-01-01	68.8
2008-04-01	69.1
2008-07-01	68.7
2008-10-01	66.3
2009-01-01	63.7
2009-04-01	60.7
2009-07-01	59.1
2009-10-01	57.9
2010-01-01	57.0
2010-04-01	57.8
2010-07-01	59.8
2010-10-01	59.4
2011-01-01	59.1
2011-04-01	60.5
2011-07-01	61.7
2011-10-01	62.0
2012-01-01	61.1
2012-04-01	62.3
2012-07-01	64.4
2012-10-01	64.1
2013-01-01	64.1
2013-04-01	64.8
2013-07-01	66.0
2013-10-01	65.3
2014-01-01	65.8
2014-04-01	66.6
2014-07-01	66.3
2014-10-01	66.5
2015-01-01	66.9
2015-04-01	68.2
2015-07-01	68.6
2015-10-01	68.7
2016-01-01	68.2
2016-04-01	69.0
2016-07-01	68.9
2016-10-01	68.8
2017-01-01	68.7
2017-04-01	69.8
2017-07-01	70.9
2017-10-01	71.0
2018-01-01	70.9
2018-04-01	71.7