Quarter	Percent
1999-04-01	47.9
1999-07-01	48.3
1999-10-01	48
2000-01-01	47.7
2000-04-01	47.2
2000-07-01	46.8
2000-10-01	46.5
2001-01-01	46.2
2001-04-01	46.1
2001-07-01	45.8
2001-10-01	45.5
2002-01-01	45.3
2002-04-01	44.9
2002-07-01	44.6
2002-10-01	44.1
2003-01-01	43.8
2003-04-01	42.7
2003-07-01	42.4
2003-10-01	42.5
2004-01-01	42.4
2004-04-01	42.1
2004-07-01	42.5
2004-10-01	41.9
2005-01-01	41.6
2005-04-01	41.7
2005-07-01	41.7
2005-10-01	41.4
2006-01-01	41.4
2006-04-01	41
2006-07-01	40.5
2006-10-01	40.7
2007-01-01	41.0
2007-04-01	40.8
2007-07-01	41.0
2007-10-01	40.2
2008-01-01	40.4
2008-04-01	40.2
2008-07-01	40.4
2008-10-01	39.7
2009-01-01	39.5
2009-04-01	39.6
2009-07-01	39.9
2009-10-01	39.9
2010-01-01	39.6
2010-04-01	40.2
2010-07-01	39.7
2010-10-01	40.5
2011-01-01	40.1
2011-04-01	40.4
2011-07-01	40.5
2011-10-01	40.3
2012-01-01	39.5
2012-04-01	39
2012-07-01	38.8
2012-10-01	38.3
2013-01-01	38
2013-04-01	37.4
2013-07-01	36.8
2013-10-01	36.5
2014-01-01	36.3
2014-04-01	36.5
2014-07-01	36.6
2014-10-01	36.4
2015-01-01	36.1
2015-04-01	36.0
2015-07-01	35.4
2015-10-01	34.8
2016-01-01	34.5
2016-04-01	34.1
2016-07-01	34.2
2016-10-01	34.1
2017-01-01	33.6
2017-04-01	33.6
2017-07-01	33.7
2017-10-01	33.3
2018-01-01	32.7
2018-04-01	32.6