Quarter	Percent
1999-04-01	59.8
1999-07-01	60
1999-10-01	60.7
2000-01-01	61.4
2000-04-01	62.5
2000-07-01	62.5
2000-10-01	63.1
2001-01-01	63.1
2001-04-01	63.9
2001-07-01	64.2
2001-10-01	64.7
2002-01-01	64.8
2002-04-01	65.5
2002-07-01	64.4
2002-10-01	64.2
2003-01-01	64.6
2003-04-01	64.9
2003-07-01	64.6
2003-10-01	65.2
2004-01-01	65.4
2004-04-01	65.8
2004-07-01	65.8
2004-10-01	66.3
2005-01-01	67.1
2005-04-01	67.4
2005-07-01	67.5
2005-10-01	67.4
2006-01-01	67.7
2006-04-01	67.7
2006-07-01	68
2006-10-01	68.5
2007-01-01	69.0
2007-04-01	69.3
2007-07-01	69.2
2007-10-01	69.3
2008-01-01	69.6
2008-04-01	69.1
2008-07-01	68.5
2008-10-01	68.6
2009-01-01	66.9
2009-04-01	66.6
2009-07-01	66.3
2009-10-01	66.1
2010-01-01	66.1
2010-04-01	65.4
2010-07-01	64.5
2010-10-01	64.6
2011-01-01	63.9
2011-04-01	64.7
2011-07-01	63.8
2011-10-01	64.5
2012-01-01	64.0
2012-04-01	64.5
2012-07-01	64.1
2012-10-01	64.9
2013-01-01	64.9
2013-04-01	65.6
2013-07-01	65.8
2013-10-01	66.3
2014-01-01	66.4
2014-04-01	66.9
2014-07-01	66.5
2014-10-01	67.6
2015-01-01	67.5
2015-04-01	68.3
2015-07-01	68.1
2015-10-01	69.6
2016-01-01	69.1
2016-04-01	69.3
2016-07-01	69.5
2016-10-01	70.0
2017-01-01	70.4
2017-04-01	70.9
2017-07-01	72.4
2017-10-01	72.9
2018-01-01	72.6
2018-04-01	73.2