Quarter	Percent
1999-01-01	15.1
1999-04-01	13.5
1999-07-01	14.6
1999-10-01	12.3
2000-01-01	14.2
2000-04-01	13.7
2000-07-01	13.6
2000-10-01	13.1
2001-01-01	13
2001-04-01	11.6
2001-07-01	11.8
2001-10-01	12.6
2002-01-01	13.2
2002-04-01	12.3
2002-07-01	14
2002-10-01	13.5
2003-01-01	15.6
2003-04-01	13.5
2003-07-01	13.2
2003-10-01	12.6
2004-01-01	15.5
2004-04-01	14.6
2004-07-01	17.2
2004-10-01	17.6
2005-01-01	20.2
2005-04-01	20.2
2005-07-01	19.2
2005-10-01	18.9
2006-01-01	19.4
2006-04-01	16.5
2006-07-01	19.7
2006-10-01	18.9
2007-01-01	18.7
2007-04-01	15.5
2007-07-01	16.7
2007-10-01	18.7
2008-01-01	19.5
2008-04-01	17.2
2008-07-01	19.2
2008-10-01	19.5
2009-01-01	25.7
2009-04-01	26.5
2009-07-01	29.4
2009-10-01	29.7
2010-01-01	30.2
2010-04-01	28.6
2010-07-01	26.9
2010-10-01	25.3
2011-01-01	28.9
2011-04-01	25
2011-07-01	27.4
2011-10-01	26.6
2012-01-01	29.8
2012-04-01	30.1
2012-07-01	29.8
2012-10-01	26.9
2013-01-01	29.5
2013-04-01	24.4
2013-07-01	26
2013-10-01	22.7
2014-01-01	19.4
2014-04-01	20
2014-07-01	20.8
2014-10-01	19.7
2015-01-01	20.6
2015-04-01	19.1
2015-07-01	17.5
2015-10-01	16.1
2016-01-01	15.3
2016-04-01	13.0
2016-07-01	12.3
2016-10-01	11.3
2017-01-01	11.0
2017-04-01	10.8
2017-07-01	8.5
2017-10-01	8.6
2018-01-01	9.4
2018-04-01	8.5