Quarter	Percent
1998-04-01	29.5
1999-01-01	27.4
1999-04-01	27.1
1999-07-01	27.8
1999-10-01	28.3
2000-01-01	27.6
2000-04-01	26.8
2000-07-01	26.8
2000-10-01	27.7
2001-01-01	28.3
2001-04-01	29.3
2001-07-01	29.9
2001-10-01	27.9
2002-01-01	27.8
2002-04-01	28
2002-07-01	27.1
2002-10-01	27.4
2003-01-01	26.9
2003-04-01	26.9
2003-07-01	26.8
2003-10-01	25.1
2004-01-01	26.1
2004-04-01	25.7
2004-07-01	25.2
2004-10-01	24.1
2005-01-01	23.1
2005-04-01	23.2
2005-07-01	22.9
2005-10-01	23.6
2006-01-01	23.8
2006-04-01	23
2006-07-01	22.9
2006-10-01	22.5
2007-01-01	22.2
2007-04-01	22.5
2007-07-01	22.3
2007-10-01	20.7
2008-01-01	20.6
2008-04-01	21.3
2008-07-01	20.8
2008-10-01	21.3
2009-01-01	19.5
2009-04-01	21.4
2009-07-01	21.3
2009-10-01	20.8
2010-01-01	19
2010-04-01	20.6
2010-07-01	20.3
2010-10-01	18.4
2011-01-01	22.2
2011-04-01	21.1
2011-07-01	20.8
2011-10-01	21
2012-01-01	21.4
2012-04-01	21.5
2012-07-01	20.6
2012-10-01	20
2013-01-01	20.6
2013-04-01	20.4
2013-07-01	19.4
2013-10-01	20.6
2014-01-01	19.5
2014-04-01	19.9
2014-07-01	19.1
2014-10-01	19.3
2015-01-01	19.0
2015-04-01	20.8
2015-07-01	19.9
2015-10-01	19.5
2016-01-01	20.5
2016-04-01	20.6
2016-07-01	20.5
2016-10-01	19.0
2017-01-01	20.3
2017-04-01	20.1
2017-07-01	21.1
2017-10-01	20.1
2018-01-01	20.2
2018-04-01	20.3