Quarter	Percent
1998-04-01	33.4
1999-04-01	33.6
2000-04-01	34.9
2001-04-01	31.8
2002-04-01	34.1
2003-04-01	32.6
2004-04-01	32.6
2005-04-01	32.4
2006-04-01	32.2
2007-04-01	30.7
2008-04-01	29.8
2009-04-01	29.8
2010-01-01	31.3
2010-04-01	31.2
2010-07-01	31.9
2010-10-01	31.2
2011-01-01	30.3
2011-04-01	30.1
2011-07-01	30.4
2011-10-01	29.6
2012-01-01	30.1
2012-04-01	29.3
2012-07-01	28.9
2012-10-01	29.3
2013-01-01	28.6
2013-04-01	27.9
2013-07-01	28.6
2013-10-01	28.4
2014-01-01	29.0
2014-04-01	28.1
2014-07-01	28.8
2014-10-01	27.6
2015-01-01	26.7
2015-04-01	27.3
2015-07-01	27.1
2015-10-01	26.0
2016-01-01	26.7
2016-04-01	25.3
2016-07-01	25.4
2016-10-01	25.3
2017-01-01	26.2
2017-04-01	24.9
2017-07-01	24.9
2017-10-01	23.8
2018-01-01	24.5
2018-04-01	23.5