Quarter	Percent
1998-01-01	54.9
1998-04-01	56.2
1998-07-01	56.2
1998-10-01	56.7
1999-01-01	56.4
1999-04-01	57.3
1999-07-01	57.2
1999-10-01	57.4
2000-01-01	57
2000-04-01	57.9
2000-07-01	58.2
2000-10-01	58.6
2001-01-01	58.7
2001-04-01	59.4
2001-07-01	59.6
2001-10-01	59.6
2002-01-01	59.8
2002-04-01	60.6
2002-07-01	60.5
2002-10-01	60.5
2003-01-01	60.4
2003-04-01	61.5
2003-07-01	60.9
2003-10-01	60.9
2004-01-01	64.2
2004-04-01	63.8
2004-07-01	63
2004-10-01	64.5
2005-01-01	63.8
2005-04-01	63.9
2005-07-01	62.6
2005-10-01	64.5
2006-01-01	64.3
2006-04-01	64.8
2006-07-01	63.5
2006-10-01	64.9
2007-01-01	63.3
2007-04-01	63.9
2007-07-01	64
2007-10-01	65.3
2008-01-01	65.4
2008-04-01	65.7
2008-07-01	64.7
2008-10-01	65.3
2009-01-01	64.7
2009-04-01	64.8
2009-07-01	63.7
2009-10-01	65.1
2010-01-01	64.6
2010-04-01	64.9
2010-07-01	63.4
2010-10-01	65.1
2011-01-01	64.7
2011-04-01	64.8
2011-07-01	63.6
2011-10-01	65.6
2012-01-01	66.6
2012-04-01	67
2012-07-01	65.3
2012-10-01	67
2013-01-01	67.1
2013-04-01	66.3
2013-07-01	64.5
2013-10-01	66.5
2014-01-01	66.7
2014-04-01	66.1
2014-07-01	65.2
2014-10-01	67.5
2015-01-01	66.3
2015-04-01	66.3
2015-07-01	64.6
2015-10-01	66.3
2016-01-01	66.0
2016-04-01	67.3
2016-07-01	66.3
2016-10-01	67.5
2017-01-01	67.3
2017-04-01	67.4
2017-07-01	67.0
2017-10-01	67.5
2018-01-01	67.3
2018-04-01	68.4