Quarter	Percent
1998-04-01	28.8
1999-04-01	27.1
2000-04-01	27.9
2001-01-01	27.5
2001-04-01	27.5
2001-07-01	26.6
2001-10-01	26.2
2002-01-01	26.1
2002-04-01	25.7
2002-07-01	25.6
2002-10-01	25.7
2003-01-01	25.9
2003-04-01	25.1
2003-07-01	24.7
2003-10-01	24.6
2004-01-01	24.4
2004-04-01	24.5
2004-07-01	24
2004-10-01	24.7
2005-01-01	23.6
2005-04-01	24.2
2005-07-01	23.2
2005-10-01	23.5
2006-01-01	23.6
2006-04-01	24.1
2006-07-01	24.1
2006-10-01	24.1
2007-01-01	24
2007-04-01	23.8
2007-07-01	23.7
2007-10-01	23.6
2008-01-01	23.7
2008-04-01	23.7
2008-07-01	23.5
2008-10-01	23.1
2009-01-01	22.7
2009-04-01	23.1
2009-07-01	22
2009-10-01	21.1
2010-01-01	21.3
2010-04-01	20.9
2010-07-01	20.4
2010-10-01	20.2
2011-01-01	21
2011-04-01	19.7
2011-07-01	20.1
2011-10-01	19.8
2012-01-01	19.7
2012-04-01	19.1
2012-07-01	19.2
2012-10-01	18.4
2013-01-01	18.7
2013-04-01	18.5
2013-07-01	18
2013-10-01	18.1
2014-01-01	18.7
2014-04-01	18.4
2014-07-01	18.7
2014-10-01	18.1
2015-01-01	18.2
2015-04-01	18.2
2015-07-01	18.8
2015-10-01	17.7
2016-01-01	17.8
2016-04-01	18.0
2016-07-01	16.8
2016-10-01	17.3
2017-01-01	17.1
2017-04-01	16.3
2017-07-01	16.9
2017-10-01	16.9
2018-01-01	16.2
2018-04-01	15.6