Quarter	Percent
1998-01-01	57.5
1998-04-01	56.3
1998-07-01	55
1998-10-01	56.1
1999-01-01	57.4
1999-04-01	57.6
1999-07-01	56.1
1999-10-01	57.9
2000-01-01	58.2
2000-04-01	57.8
2000-07-01	56.7
2000-10-01	57.2
2001-01-01	59.8
2001-04-01	59.9
2001-07-01	58.3
2001-10-01	59.5
2002-01-01	60.8
2002-04-01	60.4
2002-07-01	58.6
2002-10-01	60.5
2003-01-01	60.7
2003-04-01	60.9
2003-07-01	60
2003-10-01	61.4
2004-01-01	58.9
2004-04-01	58.6
2004-07-01	59.5
2004-10-01	60.6
2005-01-01	60.2
2005-04-01	60.3
2005-07-01	61.8
2005-10-01	62.4
2006-01-01	61.6
2006-04-01	61.7
2006-07-01	62.7
2006-10-01	63.5
2007-01-01	64.8
2007-04-01	63.6
2007-07-01	63
2007-10-01	64.6
2008-01-01	65
2008-04-01	62.9
2008-07-01	63.6
2008-10-01	65.6
2009-01-01	66.2
2009-04-01	67.2
2009-07-01	65.3
2009-10-01	66.2
2010-01-01	65.8
2010-04-01	67.1
2010-07-01	68.7
2010-10-01	67.2
2011-01-01	67.7
2011-04-01	70.3
2011-07-01	69.5
2011-10-01	67.7
2012-01-01	66.7
2012-04-01	66.8
2012-07-01	67.3
2012-10-01	67.7
2013-01-01	68.9
2013-04-01	69.4
2013-07-01	69.5
2013-10-01	69.4
2014-01-01	69.4
2014-04-01	69.5
2014-07-01	68.2
2014-10-01	68.9
2015-01-01	70.5
2015-04-01	70.5
2015-07-01	68.8
2015-10-01	68.3
2016-01-01	70.9
2016-04-01	70.0
2016-07-01	69.7
2016-10-01	68.6
2017-01-01	70.6
2017-04-01	71.2
2017-07-01	69.0
2017-10-01	69.3
2018-01-01	70.3
2018-04-01	70.1