Quarter	Percent
1998-04-01	28.1
1999-04-01	27.8
2000-04-01	28.4
2001-04-01	26.8
2002-04-01	26.1
2003-04-01	25.9
2004-04-01	26.1
2005-04-01	25.7
2006-04-01	25.3
2007-04-01	25
2008-04-01	23.4
2009-04-01	22.9
2010-01-01	24.7
2010-04-01	25.1
2010-07-01	24.4
2010-10-01	24.7
2011-01-01	23.8
2011-04-01	24.0
2011-07-01	23.9
2011-10-01	23.2
2012-01-01	23.4
2012-04-01	23.5
2012-07-01	22.9
2012-10-01	23.4
2013-01-01	23.0
2013-04-01	23.1
2013-07-01	22.9
2013-10-01	22.7
2014-01-01	22.7
2014-04-01	22.2
2014-07-01	22.1
2014-10-01	20.8
2015-01-01	21.6
2015-04-01	21.7
2015-07-01	21.5
2015-10-01	20.7
2016-01-01	19.9
2016-04-01	21.0
2016-07-01	20.9
2016-10-01	20.2
2017-01-01	20.4
2017-04-01	21.3
2017-07-01	20.6
2017-10-01	20.3
2018-01-01	20.3
2018-04-01	20.7