Quarter	Percent
2000-04-01	18.1
2001-04-01	16.1
2002-04-01	16.6
2003-04-01	17.1
2004-04-01	17.9
2005-01-01	18.4
2005-04-01	17.7
2005-07-01	17.8
2005-10-01	17.5
2006-01-01	17.5
2006-04-01	16.3
2006-07-01	16.2
2006-10-01	16.2
2007-01-01	15.6
2007-04-01	14.8
2007-07-01	14.7
2007-10-01	14.8
2008-01-01	14.7
2008-04-01	15.1
2008-07-01	15.5
2008-10-01	16.8
2009-01-01	19.3
2009-04-01	20.0
2009-07-01	20.2
2009-10-01	20.6
2010-01-01	21.7
2010-04-01	21.1
2010-07-01	20.4
2010-10-01	20.6
2011-01-01	21.6
2011-04-01	20.8
2011-07-01	20.8
2011-10-01	21.7
2012-01-01	23.2
2012-04-01	23.0
2012-07-01	23.3
2012-10-01	24.3
2013-01-01	25.1
2013-04-01	23.9
2013-07-01	23.7
2013-10-01	24.2
2014-01-01	25.0
2014-04-01	23.5
2014-07-01	23.1
2014-10-01	23.3
2015-01-01	23.3
2015-04-01	22.3
2015-07-01	21.9
2015-10-01	21.9
2016-01-01	21.9
2016-04-01	20.9
2016-07-01	20.4
2016-10-01	20.4
2017-01-01	19.9
2017-04-01	19.0
2017-07-01	18.3
2017-10-01	18.0
2018-01-01	17.8
2018-04-01	16.9