Quarter	Percent
1999-01-01	17.5
2000-01-01	17.3
2000-04-01	17.3
2000-07-01	17.9
2000-10-01	17.9
2001-01-01	18.1
2001-04-01	17.7
2001-07-01	17.9
2001-10-01	18.5
2002-01-01	18.6
2002-04-01	18.3
2002-07-01	18.4
2002-10-01	18.8
2003-01-01	18.7
2003-04-01	18.4
2003-07-01	18.6
2003-10-01	18.7
2004-01-01	18.1
2004-04-01	18.2
2004-07-01	18.3
2004-10-01	17.9
2005-01-01	17.9
2005-04-01	17.6
2005-07-01	17.2
2005-10-01	17
2006-01-01	18.6
2006-04-01	18.5
2006-07-01	17.9
2006-10-01	18.1
2007-01-01	18.9
2007-04-01	18.4
2007-07-01	18.1
2007-10-01	17.8
2008-01-01	18.3
2008-04-01	17.8
2008-07-01	17.1
2008-10-01	16.9
2009-01-01	17.1
2009-04-01	16.6
2009-07-01	16.3
2009-10-01	16.5
2010-01-01	16.2
2010-04-01	15.6
2010-07-01	15.8
2010-10-01	15.8
2011-01-01	15.9
2011-04-01	15.8
2011-07-01	15.8
2011-10-01	15.6
2012-01-01	15.7
2012-04-01	15.4
2012-07-01	15.1
2012-10-01	15.3
2013-01-01	15.9
2013-04-01	15.4
2013-07-01	15
2013-10-01	15.2
2014-01-01	15.1
2014-04-01	15.1
2014-07-01	14.7
2014-10-01	14.7
2015-01-01	14.9
2015-04-01	15.0
2015-07-01	14.8
2015-10-01	14.8
2016-01-01	15.1
2016-04-01	14.9
2016-07-01	15.0
2016-10-01	15.3
2017-01-01	15.1
2017-04-01	14.7
2017-07-01	15.1
2017-10-01	15.4
2018-01-01	15.3
2018-04-01	14.6