Quarter	Percent
1999-01-01	16.9
1999-04-01	15.6
1999-07-01	15.4
1999-10-01	15.3
2000-01-01	14.9
2000-04-01	13.9
2000-07-01	13.7
2000-10-01	13.5
2001-01-01	11
2001-04-01	10.4
2001-07-01	10.3
2001-10-01	10.7
2002-01-01	11.6
2002-04-01	11.2
2002-07-01	11.5
2002-10-01	11.7
2003-01-01	12
2003-04-01	11.3
2003-07-01	11.4
2003-10-01	11.4
2004-01-01	11.6
2004-04-01	11.1
2004-07-01	10.8
2004-10-01	10.6
2005-01-01	10.2
2005-04-01	9.4
2005-07-01	8.4
2005-10-01	8.8
2006-01-01	9.1
2006-04-01	8.5
2006-07-01	8.1
2006-10-01	8.3
2007-01-01	8.5
2007-04-01	8.0
2007-07-01	8.1
2007-10-01	8.6
2008-01-01	9.7
2008-04-01	10.4
2008-07-01	11.3
2008-10-01	13.9
2009-01-01	17.3
2009-04-01	17.9
2009-07-01	17.9
2009-10-01	18.8
2010-01-01	20
2010-04-01	20
2010-07-01	19.7
2010-10-01	20.2
2011-01-01	21.2
2011-04-01	20.8
2011-07-01	21.4
2011-10-01	22.7
2012-01-01	24.3
2012-04-01	24.5
2012-07-01	24.9
2012-10-01	25.9
2013-01-01	27.1
2013-04-01	26.2
2013-07-01	25.8
2013-10-01	25.8
2014-01-01	26
2014-04-01	24.6
2014-07-01	23.8
2014-10-01	23.8
2015-01-01	23.9
2015-04-01	22.5
2015-07-01	21.3
2015-10-01	21.0
2016-01-01	21.1
2016-04-01	20.1
2016-07-01	19.0
2016-10-01	18.7
2017-01-01	18.9
2017-04-01	17.3
2017-07-01	16.5
2017-10-01	16.6
2018-01-01	16.8
2018-04-01	15.4
2018-07-01	14.6