Quarter	Percent
1999-01-01	35.8
2000-01-01	35.5
2001-01-01	35.8
2002-01-01	36.9
2003-01-01	37.1
2003-04-01	37.0
2003-07-01	40.7
2003-10-01	37.4
2004-01-01	36.7
2004-04-01	36.6
2004-07-01	41.5
2004-10-01	37.7
2005-01-01	36
2005-04-01	37.6
2005-07-01	40.8
2005-10-01	37.9
2006-01-01	36.7
2006-04-01	37.1
2006-07-01	41.0
2006-10-01	37.6
2007-01-01	37
2007-04-01	37.1
2007-07-01	41.1
2007-10-01	38.4
2008-01-01	37.4
2008-04-01	37.3
2008-07-01	40.8
2008-10-01	38.6
2009-01-01	38.8
2009-04-01	39.2
2009-07-01	41.5
2009-10-01	38.7
2010-01-01	38.4
2010-04-01	38.6
2010-07-01	40.7
2010-10-01	38
2011-01-01	37.2
2011-04-01	37.8
2011-07-01	39.8
2011-10-01	36.9
2012-01-01	36.3
2012-04-01	36.7
2012-07-01	39.2
2012-10-01	37.5
2013-01-01	36.9
2013-04-01	36.9
2013-07-01	39.0
2013-10-01	36.7
2014-01-01	36.1
2014-04-01	36.0
2014-07-01	37.9
2014-10-01	35.9
2015-01-01	36.4
2015-04-01	36.3
2015-07-01	38.6
2015-10-01	36.9
2016-01-01	36.4
2016-04-01	36.7
2016-07-01	38.0
2016-10-01	36.7
2017-01-01	35.7
2017-04-01	36.6
2017-07-01	38.3
2017-10-01	37.0
2018-01-01	36.6
2018-04-01	36.8