Quarter	Percent
1998-01-01	13.1
1998-04-01	12.5
1998-07-01	13.4
1998-10-01	13.6
1999-01-01	15.6
1999-04-01	15.9
1999-07-01	16.8
1999-10-01	17.3
2000-01-01	18.1
2000-04-01	18.6
2000-07-01	19.1
2000-10-01	18.4
2001-01-01	18.8
2001-04-01	18.6
2001-07-01	18.9
2001-10-01	18.7
2002-01-01	19.2
2002-04-01	18.8
2002-07-01	18.5
2002-10-01	18.3
2003-01-01	17.8
2003-04-01	17.3
2003-07-01	17.9
2003-10-01	18.1
2004-01-01	19.7
2004-04-01	19.6
2004-07-01	19.1
2004-10-01	18.4
2005-01-01	18.2
2005-04-01	17.1
2005-07-01	17
2005-10-01	16.6
2006-01-01	16.1
2006-04-01	15
2006-07-01	14.3
2006-10-01	13.5
2007-01-01	12.7
2007-04-01	12.7
2007-07-01	13.1
2007-10-01	12.2
2008-01-01	12.1
2008-04-01	11.3
2008-07-01	10.4
2008-10-01	9.9
2009-01-01	11.4
2009-04-01	12.3
2009-07-01	13.3
2009-10-01	14.3
2010-01-01	15.4
2010-04-01	14.7
2010-07-01	14.3
2010-10-01	14
2011-01-01	13.9
2011-04-01	12.9
2011-07-01	13.4
2011-10-01	14.4
2012-01-01	14.5
2012-04-01	14
2012-07-01	14.6
2012-10-01	15
2013-01-01	15
2013-04-01	14.4
2013-07-01	14.5
2013-10-01	14.1
2014-01-01	13.9
2014-04-01	13.4
2014-07-01	13.6
2014-10-01	13.5
2015-01-01	13.3
2015-04-01	12.7
2015-07-01	12.9
2015-10-01	12.7
2016-01-01	11.6
2016-04-01	11.0
2016-07-01	10.6
2016-10-01	9.8
2017-01-01	8.7
2017-04-01	8.3
2017-07-01	8.2
2017-10-01	8.4
2018-01-01	7.4
2018-04-01	7.2