Quarter	Percent
1998-01-01	55.3
1998-04-01	56.7
1998-07-01	56.3
1998-10-01	55.3
1999-01-01	56.5
1999-04-01	57.9
1999-07-01	57.0
1999-10-01	57.8
2000-01-01	58.5
2000-04-01	60.1
2000-07-01	58.7
2000-10-01	58.3
2001-01-01	58.2
2001-04-01	58.4
2001-07-01	57.3
2001-10-01	57.3
2002-01-01	58.1
2002-04-01	58.2
2002-07-01	58
2002-10-01	55.9
2003-01-01	57.1
2003-04-01	58.6
2003-07-01	59.1
2003-10-01	59.6
2004-01-01	60.6
2004-04-01	62
2004-07-01	60.3
2004-10-01	61.2
2005-01-01	61.8
2005-04-01	62.8
2005-07-01	60.9
2005-10-01	62.1
2006-01-01	62.7
2006-04-01	63.3
2006-07-01	61.3
2006-10-01	62.1
2007-01-01	62.2
2007-04-01	62.9
2007-07-01	62
2007-10-01	61.5
2008-01-01	62.7
2008-04-01	62.7
2008-07-01	60.6
2008-10-01	61.7
2009-01-01	61.5
2009-04-01	63.3
2009-07-01	62.7
2009-10-01	63.6
2010-01-01	64.3
2010-04-01	65.8
2010-07-01	66.4
2010-10-01	66.7
2011-01-01	64
2011-04-01	65.4
2011-07-01	62.7
2011-10-01	64.3
2012-01-01	65.6
2012-04-01	65.7
2012-07-01	63.3
2012-10-01	65.8
2013-01-01	66.9
2013-04-01	67.5
2013-07-01	64.7
2013-10-01	65.9
2014-01-01	66.4
2014-04-01	67.5
2014-07-01	64.1
2014-10-01	66.7
2015-01-01	66.6
2015-04-01	68.9
2015-07-01	65.4
2015-10-01	67.9
2016-01-01	67.4
2016-04-01	69.9
2016-07-01	68.8
2016-10-01	68.9
2017-01-01	68.5
2017-04-01	69.1
2017-07-01	66.2
2017-10-01	66.8
2018-01-01	69.3
2018-04-01	69.6