Quarter	Percent
1999-04-01	38
2000-04-01	35.1
2001-04-01	35
2002-04-01	33.3
2003-01-01	33.5
2003-04-01	33.5
2003-07-01	33.5
2003-10-01	33.5
2004-01-01	29.6
2004-04-01	29.6
2004-07-01	29.6
2004-10-01	29.6
2005-01-01	27.8
2005-04-01	27.8
2005-07-01	27.8
2005-10-01	27.8
2006-01-01	26.2
2006-04-01	26.2
2006-07-01	26.2
2006-10-01	26.2
2007-01-01	24.6
2007-04-01	27.1
2007-07-01	26.1
2007-10-01	23.4
2008-01-01	27.3
2008-04-01	25.8
2008-07-01	27.5
2008-10-01	27.6
2009-01-01	22.5
2009-04-01	25.8
2009-07-01	24.6
2009-10-01	26
2010-01-01	22.1
2010-04-01	25.9
2010-07-01	23
2010-10-01	23.4
2011-01-01	21.3
2011-04-01	23
2011-07-01	24.1
2011-10-01	23.1
2012-01-01	21.7
2012-04-01	21.7
2012-07-01	19.5
2012-10-01	20.4
2013-01-01	18.9
2013-04-01	20
2013-07-01	19.9
2013-10-01	19.1
2014-01-01	20.9
2014-04-01	18.7
2014-07-01	19.7
2014-10-01	16.9
2015-01-01	18.4
2015-04-01	17.7
2015-07-01	19.6
2015-10-01	19.0
2016-01-01	19.1
2016-04-01	19.9
2016-07-01	19.4
2016-10-01	17.5
2017-01-01	16.2
2017-04-01	15.8
2017-07-01	14.7
2017-10-01	17.3
2018-01-01	14.3
2018-04-01	15.8