Quarter	Percent
1999-01-01	39.5
2000-01-01	38.6
2001-01-01	39.2
2002-01-01	41
2003-01-01	40.7
2003-04-01	40.5
2003-07-01	45.0
2003-10-01	41.4
2004-01-01	40.1
2004-04-01	39.9
2004-07-01	45.7
2004-10-01	41.9
2005-01-01	40.4
2005-04-01	41.2
2005-07-01	44.7
2005-10-01	41.5
2006-01-01	40.0
2006-04-01	41.4
2006-07-01	45.1
2006-10-01	41.6
2007-01-01	40.5
2007-04-01	40.2
2007-07-01	45.0
2007-10-01	42.0
2008-01-01	41.0
2008-04-01	40.9
2008-07-01	44.7
2008-10-01	42.4
2009-01-01	42.4
2009-04-01	42.6
2009-07-01	44.0
2009-10-01	42.8
2010-01-01	42.3
2010-04-01	42.1
2010-07-01	44.1
2010-10-01	42.0
2011-01-01	40.8
2011-04-01	41.3
2011-07-01	42.8
2011-10-01	40.2
2012-01-01	39.8
2012-04-01	39.7
2012-07-01	42.7
2012-10-01	41.1
2013-01-01	40.7
2013-04-01	40.4
2013-07-01	42.2
2013-10-01	39.8
2014-01-01	39.7
2014-04-01	39.2
2014-07-01	41.0
2014-10-01	39.0
2015-01-01	39.7
2015-04-01	39.8
2015-07-01	41.1
2015-10-01	40.3
2016-01-01	40.0
2016-04-01	39.4
2016-07-01	40.0
2016-10-01	39.7
2017-01-01	38.6
2017-04-01	39.8
2017-07-01	42.3
2017-10-01	40.5
2018-01-01	40.2
2018-04-01	40.2