Quarter	Percent
1999-04-01	21.6
1999-07-01	18.7
1999-10-01	20.6
2000-01-01	21
2000-04-01	20.7
2000-07-01	18.2
2000-10-01	20.5
2001-01-01	20.9
2001-04-01	20.8
2001-07-01	18.2
2001-10-01	20.5
2002-01-01	21.2
2002-04-01	21.4
2002-07-01	19.5
2002-10-01	21
2003-01-01	21.3
2003-04-01	21.4
2003-07-01	19.4
2003-10-01	20.7
2004-01-01	20.7
2004-04-01	20.8
2004-07-01	18.7
2004-10-01	20.1
2005-01-01	20.4
2005-04-01	20.1
2005-07-01	17.7
2005-10-01	19.2
2006-01-01	19.1
2006-04-01	18.8
2006-07-01	16.9
2006-10-01	18.5
2007-01-01	15.4
2007-04-01	15.3
2007-07-01	14.4
2007-10-01	15.9
2008-01-01	16.6
2008-04-01	16.1
2008-07-01	15.5
2008-10-01	17.6
2009-01-01	19.3
2009-04-01	18.5
2009-07-01	19.0
2009-10-01	20.6
2010-01-01	21.7
2010-04-01	20.8
2010-07-01	20.6
2010-10-01	22.1
2011-01-01	22.8
2011-04-01	21.8
2011-07-01	21.5
2011-10-01	21.9
2012-01-01	22.9
2012-04-01	22.0
2012-07-01	21.2
2012-10-01	22.6
2013-01-01	23.0
2013-04-01	21.4
2013-07-01	20.7
2013-10-01	21.5
2014-01-01	22.1
2014-04-01	21.5
2014-07-01	20.7
2014-10-01	21.4
2015-01-01	21.7
2015-04-01	20.8
2015-07-01	20.3
2015-10-01	21.3
2016-01-01	21.9
2016-04-01	20.5
2016-07-01	19.6
2016-10-01	21.2
2017-01-01	21.9
2017-04-01	21.3
2017-07-01	20.5
2017-10-01	21.3
2018-01-01	21.7
2018-04-01	21.2