Quarter	Percent
1999-04-01	20.7
2000-04-01	21.2
2001-04-01	21.2
2002-04-01	21.3
2003-04-01	21
2004-04-01	21
2005-01-01	19.9
2005-04-01	19.4
2005-07-01	19.1
2005-10-01	19.3
2006-01-01	19.1
2006-04-01	19
2006-07-01	18.5
2006-10-01	18.3
2007-01-01	18.4
2007-04-01	18.7
2007-07-01	17.8
2007-10-01	18.2
2008-01-01	18.1
2008-04-01	18.2
2008-07-01	17.7
2008-10-01	18
2009-01-01	18
2009-04-01	18
2009-07-01	17.6
2009-10-01	17.7
2010-01-01	17.6
2010-04-01	17.7
2010-07-01	17.4
2010-10-01	17.5
2011-01-01	17.6
2011-04-01	17.5
2011-07-01	17.3
2011-10-01	16.9
2012-01-01	17.7
2012-04-01	17.7
2012-07-01	17.1
2012-10-01	17.3
2013-01-01	17.7
2013-04-01	17.4
2013-07-01	17.3
2013-10-01	17.2
2014-01-01	17.6
2014-04-01	17.9
2014-07-01	17.1
2014-10-01	17.3
2015-01-01	17.8
2015-04-01	18.5
2015-07-01	17.7
2015-10-01	17.4
2016-01-01	18.2
2016-04-01	18.2
2016-07-01	17.5
2016-10-01	17.5
2017-01-01	18.0
2017-04-01	17.9
2017-07-01	17.4
2017-10-01	17.2
2018-01-01	17.4
2018-04-01	17.4