Quarter	Percent
1999-01-01	40.4
2000-01-01	39.7
2000-04-01	39.5
2000-07-01	40.1
2000-10-01	40.9
2001-01-01	40.6
2001-04-01	39.4
2001-07-01	39.8
2001-10-01	41.2
2002-01-01	41.3
2002-04-01	40.9
2002-07-01	41
2002-10-01	42
2003-01-01	42.2
2003-04-01	41.8
2003-07-01	41.7
2003-10-01	42.1
2004-01-01	42
2004-04-01	42.4
2004-07-01	41.8
2004-10-01	42
2005-01-01	42.8
2005-04-01	42.4
2005-07-01	40.9
2005-10-01	41.5
2006-01-01	43.6
2006-04-01	43.7
2006-07-01	42.4
2006-10-01	43.1
2007-01-01	44.3
2007-04-01	43.9
2007-07-01	42.9
2007-10-01	43
2008-01-01	43.7
2008-04-01	43.5
2008-07-01	42.5
2008-10-01	42.5
2009-01-01	42.6
2009-04-01	42.5
2009-07-01	41.9
2009-10-01	41.8
2010-01-01	42
2010-04-01	41.4
2010-07-01	41
2010-10-01	41.5
2011-01-01	41.7
2011-04-01	41.3
2011-07-01	40.8
2011-10-01	40.7
2012-01-01	40.8
2012-04-01	40.4
2012-07-01	39.9
2012-10-01	39.9
2013-01-01	40.6
2013-04-01	40.2
2013-07-01	39.4
2013-10-01	39.2
2014-01-01	38.9
2014-04-01	39.3
2014-07-01	38.8
2014-10-01	38.5
2015-01-01	38.8
2015-04-01	38.9
2015-07-01	38.4
2015-10-01	38.3
2016-01-01	38.2
2016-04-01	38.1
2016-07-01	37.8
2016-10-01	38.0
2017-01-01	37.6
2017-04-01	37.0
2017-07-01	37.3
2017-10-01	37.7
2018-01-01	37.2
2018-04-01	36.4