Quarter	Percent
1999-04-01	45.4
2000-04-01	45.4
2001-04-01	44.8
2002-04-01	44.6
2003-04-01	44.1
2004-04-01	44.4
2005-01-01	42.7
2005-04-01	42.9
2005-07-01	42.7
2005-10-01	42.4
2006-01-01	41.9
2006-04-01	41.8
2006-07-01	41.5
2006-10-01	41.2
2007-01-01	41.7
2007-04-01	41.4
2007-07-01	40.8
2007-10-01	40.5
2008-01-01	41.3
2008-04-01	41.5
2008-07-01	40.6
2008-10-01	40.3
2009-01-01	41
2009-04-01	40.7
2009-07-01	40.5
2009-10-01	39.4
2010-01-01	40.2
2010-04-01	40.1
2010-07-01	39.8
2010-10-01	39.4
2011-01-01	39.3
2011-04-01	38.7
2011-07-01	38.2
2011-10-01	38.1
2012-01-01	38.9
2012-04-01	38.5
2012-07-01	38
2012-10-01	37.9
2013-01-01	37.7
2013-04-01	37.4
2013-07-01	37.2
2013-10-01	37.3
2014-01-01	37.1
2014-04-01	36.9
2014-07-01	36.6
2014-10-01	36.7
2015-01-01	36.8
2015-04-01	36.7
2015-07-01	36.6
2015-10-01	36.3
2016-01-01	35.9
2016-04-01	36.0
2016-07-01	35.2
2016-10-01	35.1
2017-01-01	35.6
2017-04-01	35.5
2017-07-01	34.8
2017-10-01	34.5
2018-01-01	35.4
2018-04-01	35.4