Quarter	Percent
1999-04-01	21.7
2000-04-01	20.2
2001-04-01	20.2
2002-04-01	19
2003-01-01	19.6
2003-04-01	19.6
2003-07-01	19.6
2003-10-01	19.6
2004-01-01	17
2004-04-01	17
2004-07-01	17
2004-10-01	17
2005-01-01	16.1
2005-04-01	16.1
2005-07-01	16.1
2005-10-01	16.1
2006-01-01	15.5
2006-04-01	15.5
2006-07-01	15.5
2006-10-01	15.5
2007-01-01	14.7
2007-04-01	16.3
2007-07-01	15.3
2007-10-01	14.7
2008-01-01	17.3
2008-04-01	15.9
2008-07-01	15.7
2008-10-01	17.4
2009-01-01	14.3
2009-04-01	15.8
2009-07-01	14.9
2009-10-01	16
2010-01-01	13.5
2010-04-01	15.9
2010-07-01	13.6
2010-10-01	14.3
2011-01-01	13.1
2011-04-01	14.1
2011-07-01	15.5
2011-10-01	14.9
2012-01-01	13.7
2012-04-01	13.1
2012-07-01	12.1
2012-10-01	13
2013-01-01	12.5
2013-04-01	13.2
2013-07-01	11.9
2013-10-01	12.2
2014-01-01	12.2
2014-04-01	12.2
2014-07-01	12.5
2014-10-01	11
2015-01-01	12.3
2015-04-01	12.1
2015-07-01	12.5
2015-10-01	12.3
2016-01-01	12.9
2016-04-01	13.3
2016-07-01	13.0
2016-10-01	12.1
2017-01-01	12.0
2017-04-01	12.1
2017-07-01	11.7
2017-10-01	12.3
2018-01-01	11.0
2018-04-01	11.7