Quarter	Percent
1998-01-01	66.1
1998-04-01	66.7
1998-07-01	67.4
1998-10-01	67
1999-01-01	66.5
1999-04-01	67.1
1999-07-01	67.9
1999-10-01	67.6
2000-01-01	66.9
2000-04-01	67.6
2000-07-01	68.7
2000-10-01	68.8
2001-01-01	68.1
2001-04-01	68.1
2001-07-01	69.1
2001-10-01	68.9
2002-01-01	68.7
2002-04-01	68.9
2002-07-01	69.4
2002-10-01	69.3
2003-01-01	69
2003-04-01	69.5
2003-07-01	70
2003-10-01	69.9
2004-01-01	69.4
2004-04-01	70.4
2004-07-01	70.7
2004-10-01	70.1
2005-01-01	69.5
2005-04-01	70.2
2005-07-01	70
2005-10-01	69.9
2006-01-01	69.9
2006-04-01	71
2006-07-01	70.6
2006-10-01	70.2
2007-01-01	69.8
2007-04-01	70.9
2007-07-01	71.1
2007-10-01	70.5
2008-01-01	69.6
2008-04-01	70.7
2008-07-01	70.6
2008-10-01	69.7
2009-01-01	68.4
2009-04-01	68.9
2009-07-01	68.7
2009-10-01	68
2010-01-01	67.4
2010-04-01	67.8
2010-07-01	67.5
2010-10-01	67.4
2011-01-01	67
2011-04-01	67.6
2011-07-01	67.6
2011-10-01	66.8
2012-01-01	66.1
2012-04-01	66.7
2012-07-01	66.8
2012-10-01	65.9
2013-01-01	64.5
2013-04-01	64.6
2013-07-01	64.9
2013-10-01	64.6
2014-01-01	63.8
2014-04-01	64.8
2014-07-01	65.3
2014-10-01	64.8
2015-01-01	64.2
2015-04-01	65.3
2015-07-01	66.6
2015-10-01	65.9
2016-01-01	65.3
2016-04-01	66.9
2016-07-01	67.0
2016-10-01	66.5
2017-01-01	66.2
2017-04-01	67.1
2017-07-01	67.7
2017-10-01	67.1
2018-01-01	66.5
2018-04-01	68.0