Quarter	Percent
1998-01-01	12.1
1998-04-01	11.1
1998-07-01	11
1998-10-01	11.6
1999-01-01	12.4
1999-04-01	12.1
1999-07-01	11.9
1999-10-01	12.9
2000-01-01	12.5
2000-04-01	11.5
2000-07-01	11.1
2000-10-01	11.1
2001-01-01	11.4
2001-04-01	10.6
2001-07-01	10.4
2001-10-01	11.4
2002-01-01	11.6
2002-04-01	10.2
2002-07-01	10
2002-10-01	10.4
2003-01-01	10.6
2003-04-01	9.6
2003-07-01	9.5
2003-10-01	10.2
2004-01-01	11.6
2004-04-01	10.5
2004-07-01	10.3
2004-10-01	10.6
2005-01-01	10.7
2005-04-01	9.9
2005-07-01	10
2005-10-01	10
2006-01-01	10
2006-04-01	9.0
2006-07-01	8.6
2006-10-01	9.1
2007-01-01	9.4
2007-04-01	8.3
2007-07-01	8.1
2007-10-01	8.3
2008-01-01	8.5
2008-04-01	7.4
2008-07-01	7.4
2008-10-01	8.2
2009-01-01	9.6
2009-04-01	9.2
2009-07-01	9.6
2009-10-01	10.7
2010-01-01	12.1
2010-04-01	12.2
2010-07-01	12.8
2010-10-01	14.6
2011-01-01	16.3
2011-04-01	16.8
2011-07-01	18.2
2011-10-01	21.2
2012-01-01	23.1
2012-04-01	24
2012-07-01	25.2
2012-10-01	26.5
2013-01-01	27.8
2013-04-01	27.5
2013-07-01	27.4
2013-10-01	28
2014-01-01	28
2014-04-01	26.8
2014-07-01	25.7
2014-10-01	26.3
2015-01-01	26.9
2015-04-01	24.8
2015-07-01	24.2
2015-10-01	24.6
2016-01-01	25.1
2016-04-01	23.3
2016-07-01	22.8
2016-10-01	23.7
2017-01-01	23.5
2017-04-01	21.3
2017-07-01	20.4
2017-10-01	21.4
2018-01-01	21.4
2018-04-01	19.2