Quarter	Percent
1999-04-01	41.2
2000-01-01	43.8
2000-04-01	41.9
2000-07-01	40.2
2000-10-01	44.8
2001-01-01	43.2
2001-04-01	47
2001-07-01	47
2001-10-01	47.7
2002-01-01	45.8
2002-04-01	51.4
2002-07-01	54
2002-10-01	51.7
2003-01-01	50.1
2003-04-01	52.7
2003-07-01	49.4
2003-10-01	51.5
2004-01-01	57.7
2004-04-01	56.1
2004-07-01	53.4
2004-10-01	52.8
2005-01-01	55.9
2005-04-01	57.6
2005-07-01	60.2
2005-10-01	56.9
2006-01-01	56.9
2006-04-01	65.2
2006-07-01	61.5
2006-10-01	58.8
2007-01-01	62.9
2007-04-01	66
2007-07-01	58.9
2007-10-01	57.1
2008-01-01	60.3
2008-04-01	61.9
2008-07-01	62.1
2008-10-01	65.4
2009-01-01	66.9
2009-04-01	65.5
2009-07-01	66.4
2009-10-01	65.1
2010-01-01	65.1
2010-04-01	64.2
2010-07-01	65.8
2010-10-01	61.9
2011-01-01	63.9
2011-04-01	64.2
2011-07-01	61.8
2011-10-01	64.4
2012-01-01	66.8
2012-04-01	67.1
2012-07-01	65.8
2012-10-01	60.1
2013-01-01	67
2013-04-01	71.4
2013-07-01	65.4
2013-10-01	62.1
2014-01-01	62.4
2014-04-01	65.4
2014-07-01	70.4
2014-10-01	67.9
2015-01-01	65.2
2015-04-01	69.0
2015-07-01	74.5
2015-10-01	69.1
2016-01-01	68.6
2016-04-01	73.5
2016-07-01	73.4
2016-10-01	70.1
2017-01-01	70.9
2017-04-01	70.4
2017-07-01	72.3
2017-10-01	75.9
2018-01-01	75.3
2018-04-01	72.9