Quarter	Percent
1999-04-01	39.7
1999-07-01	39.4
1999-10-01	40.2
2000-01-01	41
2000-04-01	41.4
2000-07-01	42
2000-10-01	42.3
2001-01-01	42.6
2001-04-01	43.1
2001-07-01	43
2001-10-01	43.4
2002-01-01	43.9
2002-04-01	44.6
2002-07-01	44.5
2002-10-01	45.1
2003-01-01	45.3
2003-04-01	46.3
2003-07-01	46.7
2003-10-01	46.8
2004-01-01	46.6
2004-04-01	47.2
2004-07-01	46.6
2004-10-01	47.3
2005-01-01	47.9
2005-04-01	48.2
2005-07-01	47.8
2005-10-01	48.1
2006-01-01	48.5
2006-04-01	48.9
2006-07-01	49.1
2006-10-01	49.4
2007-01-01	49.1
2007-04-01	48.8
2007-07-01	48.6
2007-10-01	48.9
2008-01-01	48.8
2008-04-01	49
2008-07-01	48.7
2008-10-01	49.5
2009-01-01	49.2
2009-04-01	49.3
2009-07-01	49.1
2009-10-01	49.1
2010-01-01	49.7
2010-04-01	49
2010-07-01	50
2010-10-01	49.2
2011-01-01	49.6
2011-04-01	49.4
2011-07-01	49.7
2011-10-01	49.3
2012-01-01	50.5
2012-04-01	50.9
2012-07-01	50.9
2012-10-01	51.8
2013-01-01	52.1
2013-04-01	53
2013-07-01	53.1
2013-10-01	53.9
2014-01-01	54.2
2014-04-01	54.3
2014-07-01	54.0
2014-10-01	55.2
2015-01-01	55.5
2015-04-01	55.3
2015-07-01	56.2
2015-10-01	56.8
2016-01-01	56.8
2016-04-01	58.0
2016-07-01	57.1
2016-10-01	57.7
2017-01-01	58.5
2017-04-01	58.7
2017-07-01	59.1
2017-10-01	60.0
2018-01-01	60.1
2018-04-01	60.4