Quarter	Percent
1999-04-01	36.3
2000-01-01	37.4
2000-04-01	38.6
2000-07-01	39.5
2000-10-01	40.4
2001-01-01	40
2001-04-01	39.9
2001-07-01	39.9
2001-10-01	40.9
2002-01-01	41.7
2002-04-01	42.9
2002-07-01	44.2
2002-10-01	44.3
2003-01-01	45.4
2003-04-01	45.5
2003-07-01	45.6
2003-10-01	45.5
2004-01-01	46.4
2004-04-01	46.3
2004-07-01	47.1
2004-10-01	47.7
2005-01-01	47.7
2005-04-01	48.1
2005-07-01	48.3
2005-10-01	48.3
2006-01-01	48.2
2006-04-01	49.3
2006-07-01	50
2006-10-01	50.8
2007-01-01	51.7
2007-04-01	52.8
2007-07-01	53.3
2007-10-01	53.2
2008-01-01	53.7
2008-04-01	54.5
2008-07-01	55.1
2008-10-01	55.7
2009-01-01	56.7
2009-04-01	56.4
2009-07-01	57.1
2009-10-01	57.2
2010-01-01	55.3
2010-04-01	55.7
2010-07-01	56.1
2010-10-01	56.5
2011-01-01	56.7
2011-04-01	57.4
2011-07-01	58.1
2011-10-01	59.4
2012-01-01	59.8
2012-04-01	60.8
2012-07-01	60.9
2012-10-01	61.8
2013-01-01	62.3
2013-04-01	63.2
2013-07-01	64.0
2013-10-01	64.4
2014-01-01	64.2
2014-04-01	64.7
2014-07-01	65.1
2014-10-01	65.5
2015-01-01	66.4
2015-04-01	67.3
2015-07-01	67.1
2015-10-01	67.6
2016-01-01	68.2
2016-04-01	68.4
2016-07-01	68.2
2016-10-01	68.7
2017-01-01	69.0
2017-04-01	69.8
2017-07-01	69.4
2017-10-01	69.9
2018-01-01	69.9
2018-04-01	70.7