Quarter	Percent
1998-04-01	35.6
1998-10-01	37.2
1999-04-01	37.8
1999-10-01	37.5
2000-04-01	38.3
2000-10-01	37.4
2001-04-01	36.8
2001-10-01	37.1
2002-01-01	38.2
2002-04-01	35.2
2002-07-01	36.9
2002-10-01	34.9
2003-01-01	36.6
2003-04-01	35.4
2003-07-01	34.1
2003-10-01	36.2
2004-01-01	34.8
2004-04-01	35.9
2004-07-01	34.6
2004-10-01	34.2
2005-01-01	36.0
2005-04-01	34.7
2005-07-01	35.6
2005-10-01	34.7
2006-01-01	35.2
2006-04-01	32.9
2006-07-01	32.9
2006-10-01	33.4
2007-01-01	34.0
2007-04-01	32.4
2007-07-01	31.8
2007-10-01	30.7
2008-01-01	29.9
2008-04-01	29.2
2008-07-01	29.6
2008-10-01	29.9
2009-01-01	28.0
2009-04-01	29.3
2009-07-01	30.5
2009-10-01	29.4
2010-01-01	29.6
2010-04-01	29.0
2010-07-01	28.4
2010-10-01	29.6
2011-01-01	30.9
2011-04-01	29.5
2011-07-01	29.5
2011-10-01	29.8
2012-01-01	28.7
2012-04-01	27.7
2012-07-01	27.7
2012-10-01	28.1
2013-01-01	28.6
2013-04-01	28.4
2013-07-01	27.3
2013-10-01	29.4
2014-01-01	27.8
2014-04-01	27.9
2014-07-01	28.6
2014-10-01	29.4
2015-01-01	28.3
2015-04-01	27.4
2015-07-01	26.5
2015-10-01	26.6
2016-01-01	26.1
2016-04-01	26.0
2016-07-01	26.3
2016-10-01	25.7
2017-01-01	26.8
2017-04-01	26.0
2017-07-01	24.8
2017-10-01	25.2
2018-01-01	24.9
2018-04-01	24.7