Quarter	Percent
1999-04-01	33.8
2000-04-01	33.4
2001-04-01	33.6
2002-04-01	33.8
2003-04-01	35.8
2004-04-01	37.9
2005-01-01	42.2
2005-04-01	42.9
2005-07-01	43
2005-10-01	44.7
2006-01-01	45.4
2006-04-01	45.7
2006-07-01	46.3
2006-10-01	47.9
2007-01-01	47.2
2007-04-01	49.2
2007-07-01	49
2007-10-01	50.1
2008-01-01	49.4
2008-04-01	50.8
2008-07-01	50.6
2008-10-01	51.3
2009-01-01	51.9
2009-04-01	53.3
2009-07-01	52.5
2009-10-01	53.8
2010-01-01	54.9
2010-04-01	54.1
2010-07-01	54.5
2010-10-01	54.9
2011-01-01	56.3
2011-04-01	56.6
2011-07-01	57.1
2011-10-01	57.1
2012-01-01	57.4
2012-04-01	57.9
2012-07-01	58.6
2012-10-01	58.7
2013-01-01	60.1
2013-04-01	60.3
2013-07-01	61.2
2013-10-01	61.6
2014-01-01	62.1
2014-04-01	62.9
2014-07-01	63.2
2014-10-01	63.4
2015-01-01	63.5
2015-04-01	63.6
2015-07-01	63.9
2015-10-01	64.3
2016-01-01	65.1
2016-04-01	65.9
2016-07-01	66.3
2016-10-01	66.3
2017-01-01	66.8
2017-04-01	67.4
2017-07-01	67.5
2017-10-01	68.1
2018-01-01	68.0
2018-04-01	68.1