Quarter	Percent
1999-04-01	48.8
2000-01-01	48.4
2000-04-01	49.9
2000-07-01	51.1
2000-10-01	51.4
2001-01-01	50.8
2001-04-01	50.5
2001-07-01	50.6
2001-10-01	52.3
2002-01-01	52.5
2002-04-01	54.9
2002-07-01	55.4
2002-10-01	55.7
2003-01-01	56.9
2003-04-01	56.9
2003-07-01	56.6
2003-10-01	56.5
2004-01-01	56.9
2004-04-01	56.4
2004-07-01	56.8
2004-10-01	57.4
2005-01-01	56.7
2005-04-01	57.3
2005-07-01	57.2
2005-10-01	56.6
2006-01-01	55.9
2006-04-01	57.9
2006-07-01	58.6
2006-10-01	59.4
2007-01-01	60.5
2007-04-01	61.6
2007-07-01	62.1
2007-10-01	62
2008-01-01	62.1
2008-04-01	63.2
2008-07-01	64.4
2008-10-01	64.9
2009-01-01	65.3
2009-04-01	65.4
2009-07-01	65.8
2009-10-01	65.1
2010-01-01	63.6
2010-04-01	64.7
2010-07-01	64.8
2010-10-01	64.9
2011-01-01	63.3
2011-04-01	64.1
2011-07-01	64.9
2011-10-01	65.6
2012-01-01	66.0
2012-04-01	67.0
2012-07-01	67.2
2012-10-01	67.4
2013-01-01	67.6
2013-04-01	68.3
2013-07-01	69.5
2013-10-01	70.1
2014-01-01	68.3
2014-04-01	69.4
2014-07-01	69.6
2014-10-01	70.2
2015-01-01	70.8
2015-04-01	71.0
2015-07-01	70.9
2015-10-01	71.7
2016-01-01	72.2
2016-04-01	72.1
2016-07-01	72.8
2016-10-01	74.1
2017-01-01	73.8
2017-04-01	74.6
2017-07-01	75.0
2017-10-01	75.6
2018-01-01	75.4
2018-04-01	76.2