Quarter	Percent
1999-01-01	13.4
2000-01-01	18.8
2000-04-01	18.6
2000-07-01	17.8
2000-10-01	18.4
2001-01-01	20
2001-04-01	20.3
2001-07-01	20
2001-10-01	20.3
2002-01-01	21.3
2002-04-01	21
2002-07-01	21.7
2002-10-01	20.9
2003-01-01	21.1
2003-04-01	20.3
2003-07-01	20.9
2003-10-01	20.7
2004-01-01	21.6
2004-04-01	20
2004-07-01	19.5
2004-10-01	19.8
2005-01-01	20.3
2005-04-01	19.4
2005-07-01	19.4
2005-10-01	18.6
2006-01-01	17
2006-04-01	15
2006-07-01	14.5
2006-10-01	13.9
2007-01-01	12.2
2007-04-01	10.2
2007-07-01	9.9
2007-10-01	9.5
2008-01-01	8.8
2008-04-01	7.8
2008-07-01	7.9
2008-10-01	7.7
2009-01-01	9.0
2009-04-01	8.4
2009-07-01	8.7
2009-10-01	8.9
2010-01-01	10.8
2010-04-01	9.9
2010-07-01	9.8
2010-10-01	10
2011-01-01	10.2
2011-04-01	10.2
2011-07-01	10.7
2011-10-01	10.9
2012-01-01	11.1
2012-04-01	10.8
2012-07-01	11
2012-10-01	11.2
2013-01-01	12
2013-04-01	11.4
2013-07-01	10.9
2013-10-01	10.6
2014-01-01	11.1
2014-04-01	9.8
2014-07-01	9.1
2014-10-01	8.8
2015-01-01	8.9
2015-04-01	7.6
2015-07-01	7.6
2015-10-01	7.2
2016-01-01	7.1
2016-04-01	6.1
2016-07-01	6.3
2016-10-01	5.7
2017-01-01	5.4
2017-04-01	4.8
2017-07-01	5.0
2017-10-01	4.7
2018-01-01	4.3
2018-04-01	3.5