Quarter	Percent
1999-01-01	23.6
2000-01-01	23
2000-04-01	22.9
2000-07-01	23.9
2000-10-01	24.3
2001-01-01	24
2001-04-01	23
2001-07-01	23.5
2001-10-01	24.5
2002-01-01	24.4
2002-04-01	23.8
2002-07-01	23.9
2002-10-01	24.8
2003-01-01	24.4
2003-04-01	23.8
2003-07-01	24.3
2003-10-01	24.5
2004-01-01	23.9
2004-04-01	24.1
2004-07-01	24.2
2004-10-01	23.8
2005-01-01	24.3
2005-04-01	24
2005-07-01	23.1
2005-10-01	22.9
2006-01-01	24.9
2006-04-01	25
2006-07-01	24
2006-10-01	24.5
2007-01-01	25.4
2007-04-01	24.5
2007-07-01	23.9
2007-10-01	23.8
2008-01-01	24.7
2008-04-01	24.3
2008-07-01	23.1
2008-10-01	22.8
2009-01-01	23.1
2009-04-01	22.7
2009-07-01	22.4
2009-10-01	22
2010-01-01	21.7
2010-04-01	21.1
2010-07-01	21.4
2010-10-01	21.5
2011-01-01	21.3
2011-04-01	21.4
2011-07-01	21.5
2011-10-01	21.1
2012-01-01	21.1
2012-04-01	20.9
2012-07-01	20.7
2012-10-01	20.8
2013-01-01	21.4
2013-04-01	21.2
2013-07-01	20.6
2013-10-01	20.4
2014-01-01	20.2
2014-04-01	20.9
2014-07-01	20.4
2014-10-01	19.9
2015-01-01	20.3
2015-04-01	20.4
2015-07-01	20.5
2015-10-01	20.5
2016-01-01	20.8
2016-04-01	20.8
2016-07-01	21.0
2016-10-01	21.5
2017-01-01	21.0
2017-04-01	20.6
2017-07-01	21.7
2017-10-01	21.7
2018-01-01	21.0
2018-04-01	20.6