Quarter	Percent
1999-04-01	37.2
2000-04-01	37.6
2001-04-01	37.4
2002-04-01	37.5
2003-04-01	37.3
2004-04-01	37.6
2005-01-01	36.2
2005-04-01	36.1
2005-07-01	35.9
2005-10-01	35.9
2006-01-01	35.7
2006-04-01	35.5
2006-07-01	35.2
2006-10-01	34.9
2007-01-01	35.6
2007-04-01	35.3
2007-07-01	34.7
2007-10-01	34.6
2008-01-01	35.2
2008-04-01	35.3
2008-07-01	34.4
2008-10-01	34.5
2009-01-01	35
2009-04-01	34.9
2009-07-01	34.5
2009-10-01	33.9
2010-01-01	34.4
2010-04-01	34.4
2010-07-01	34
2010-10-01	33.8
2011-01-01	33.8
2011-04-01	33.2
2011-07-01	32.8
2011-10-01	32.7
2012-01-01	33.4
2012-04-01	33.1
2012-07-01	32.4
2012-10-01	32.5
2013-01-01	32.7
2013-04-01	32.2
2013-07-01	32
2013-10-01	32.1
2014-01-01	32.2
2014-04-01	32.1
2014-07-01	31.5
2014-10-01	31.6
2015-01-01	31.9
2015-04-01	32.1
2015-07-01	31.7
2015-10-01	31.3
2016-01-01	31.3
2016-04-01	31.4
2016-07-01	30.5
2016-10-01	30.4
2017-01-01	31.0
2017-04-01	30.8
2017-07-01	30.2
2017-10-01	30.0
2018-01-01	30.7
2018-04-01	30.7