Quarter	Percent
1998-01-01	39.6
1999-01-01	41.6
1999-04-01	40.7
1999-07-01	39.1
1999-10-01	37.5
2000-01-01	41.4
2000-04-01	42.1
2000-07-01	40.8
2000-10-01	40.7
2001-01-01	37.9
2001-04-01	40.9
2001-07-01	40.6
2001-10-01	40.6
2002-01-01	38
2002-04-01	39.9
2002-07-01	40
2002-10-01	40.4
2003-01-01	39.5
2003-04-01	41.2
2003-07-01	40.4
2003-10-01	40.5
2004-01-01	35
2004-04-01	37.7
2004-07-01	36.9
2004-10-01	36.9
2005-01-01	37.4
2005-04-01	38.5
2005-07-01	38.5
2005-10-01	39.7
2006-01-01	41
2006-04-01	42
2006-07-01	42.3
2006-10-01	42.2
2007-01-01	43.3
2007-04-01	46.6
2007-07-01	47.6
2007-10-01	46.3
2008-01-01	49.4
2008-04-01	49.6
2008-07-01	48.2
2008-10-01	48.5
2009-01-01	47.6
2009-04-01	49.5
2009-07-01	49.8
2009-10-01	49.4
2010-01-01	49.2
2010-04-01	50
2010-07-01	50.9
2010-10-01	49.5
2011-01-01	47.5
2011-04-01	48.7
2011-07-01	48.6
2011-10-01	47.9
2012-01-01	47.4
2012-04-01	50.3
2012-07-01	51.5
2012-10-01	51.5
2013-01-01	50.6
2013-04-01	53.4
2013-07-01	53.1
2013-10-01	54.1
2014-01-01	52.5
2014-04-01	55
2014-07-01	54.7
2014-10-01	54.9
2015-01-01	53.2
2015-04-01	53.5
2015-07-01	54.3
2015-10-01	55.3
2016-01-01	56.4
2016-04-01	57.6
2016-07-01	58.3
2016-10-01	58.0
2017-01-01	58.3
2017-04-01	59.9
2017-07-01	60.2
2017-10-01	62.1
2018-01-01	62.3
2018-04-01	63.2