Quarter	Percent
1998-01-01	17.8
1998-04-01	18.0
1998-07-01	18.5
1998-10-01	18.2
1999-01-01	18.1
1999-04-01	18.1
1999-07-01	18.1
1999-10-01	17.9
2000-01-01	18.1
2000-04-01	18.1
2000-07-01	18.3
2000-10-01	18.4
2001-01-01	17.9
2001-04-01	18.3
2001-07-01	18.2
2001-10-01	18.4
2002-01-01	18.8
2002-04-01	18.5
2002-07-01	18.5
2002-10-01	18.2
2003-01-01	18.6
2003-04-01	18.6
2003-07-01	19.5
2003-10-01	19.3
2004-01-01	19.3
2004-04-01	19.2
2004-07-01	19.1
2004-10-01	18.8
2005-01-01	19.1
2005-04-01	18.4
2005-07-01	18.1
2005-10-01	18
2006-01-01	18.2
2006-04-01	18.7
2006-07-01	19
2006-10-01	19.1
2007-01-01	19.4
2007-04-01	19.6
2007-07-01	19.9
2007-10-01	19.9
2008-01-01	20.3
2008-04-01	20.3
2008-07-01	20.5
2008-10-01	20.6
2009-01-01	20.8
2009-04-01	20.2
2009-07-01	19.9
2009-10-01	19.6
2010-01-01	20.2
2010-04-01	20.2
2010-07-01	20.3
2010-10-01	20.2
2011-01-01	20.1
2011-04-01	19.6
2011-07-01	19.5
2011-10-01	19.1
2012-01-01	19.7
2012-04-01	19.3
2012-07-01	18.8
2012-10-01	18.6
2013-01-01	18.6
2013-04-01	17.8
2013-07-01	17.9
2013-10-01	17.9
2014-01-01	18.3
2014-04-01	18.7
2014-07-01	18.8
2014-10-01	18
2015-01-01	18.4
2015-04-01	18.7
2015-07-01	18.7
2015-10-01	18.5
2016-01-01	18.4
2016-04-01	17.9
2016-07-01	18.0
2016-10-01	17.5
2017-01-01	18.2
2017-04-01	17.9
2017-07-01	17.6
2017-10-01	17.8
2018-01-01	18.1
2018-04-01	17.8