Quarter	Percent
1999-01-01	32
2000-01-01	32.9
2001-01-01	34.9
2002-01-01	38.1
2003-01-01	39.6
2003-04-01	40.6
2003-07-01	41.5
2003-10-01	41.8
2004-01-01	42.4
2004-04-01	41.6
2004-07-01	41.6
2004-10-01	41
2005-01-01	41.4
2005-04-01	41.9
2005-07-01	41.7
2005-10-01	41.1
2006-01-01	40.8
2006-04-01	41
2006-07-01	40.4
2006-10-01	40.0
2007-01-01	40.2
2007-04-01	41
2007-07-01	40.7
2007-10-01	40.1
2008-01-01	39.9
2008-04-01	40.7
2008-07-01	40.7
2008-10-01	41
2009-01-01	40.8
2009-04-01	41.8
2009-07-01	41.7
2009-10-01	41.7
2010-01-01	41.3
2010-04-01	42.4
2010-07-01	42.7
2010-10-01	42.6
2011-01-01	42.8
2011-04-01	43.8
2011-07-01	44.3
2011-10-01	45.3
2012-01-01	45.9
2012-04-01	47.1
2012-07-01	48.3
2012-10-01	48.9
2013-01-01	48.1
2013-04-01	48.5
2013-07-01	48.6
2013-10-01	48.4
2014-01-01	48.4
2014-04-01	48.4
2014-07-01	48.9
2014-10-01	49.7
2015-01-01	50.1
2015-04-01	50.8
2015-07-01	51.0
2015-10-01	50.9
2016-01-01	51.0
2016-04-01	51.4
2016-07-01	52.1
2016-10-01	51.8
2017-01-01	51.6
2017-04-01	53.0
2017-07-01	52.6
2017-10-01	53.8
2018-01-01	53.2
2018-04-01	54.2