Quarter	Percent
1998-01-01	17.8
1998-04-01	16.7
1998-07-01	16.9
1998-10-01	17.6
1999-01-01	18.1
1999-04-01	18.2
1999-07-01	17.9
1999-10-01	19
2000-01-01	18.6
2000-04-01	17
2000-07-01	16.7
2000-10-01	16.6
2001-01-01	16.9
2001-04-01	15.9
2001-07-01	15.4
2001-10-01	16.8
2002-01-01	17.1
2002-04-01	15.4
2002-07-01	15.2
2002-10-01	15.5
2003-01-01	15.8
2003-04-01	14.5
2003-07-01	14.6
2003-10-01	15.6
2004-01-01	17.2
2004-04-01	16
2004-07-01	15.9
2004-10-01	16.2
2005-01-01	16.2
2005-04-01	15.3
2005-07-01	15.2
2005-10-01	15.1
2006-01-01	14.8
2006-04-01	13.5
2006-07-01	13.1
2006-10-01	13.7
2007-01-01	14.1
2007-04-01	12.8
2007-07-01	12.4
2007-10-01	12.4
2008-01-01	12.4
2008-04-01	11.1
2008-07-01	10.9
2008-10-01	11.8
2009-01-01	13.1
2009-04-01	12.7
2009-07-01	13.2
2009-10-01	14.2
2010-01-01	15.7
2010-04-01	15.4
2010-07-01	16.2
2010-10-01	18.1
2011-01-01	19.7
2011-04-01	20.1
2011-07-01	21.6
2011-10-01	24.7
2012-01-01	26.7
2012-04-01	27.4
2012-07-01	29
2012-10-01	29.8
2013-01-01	31.2
2013-04-01	31.2
2013-07-01	31.3
2013-10-01	31.8
2014-01-01	31.5
2014-04-01	30.4
2014-07-01	29.2
2014-10-01	29.6
2015-01-01	30.6
2015-04-01	28.3
2015-07-01	28.2
2015-10-01	28.4
2016-01-01	29.5
2016-04-01	27.6
2016-07-01	27.2
2016-10-01	28.2
2017-01-01	27.8
2017-04-01	25.5
2017-07-01	25.0
2017-10-01	26.1
2018-01-01	26.2
2018-04-01	23.7