Quarter	Percent
1998-01-01	28.5
1998-04-01	28.9
1998-07-01	29.4
1998-10-01	29.5
1999-01-01	29.2
1999-04-01	29.6
1999-07-01	30.1
1999-10-01	30.1
2000-01-01	29.7
2000-04-01	30.4
2000-07-01	31
2000-10-01	31.3
2001-01-01	31.2
2001-04-01	31.5
2001-07-01	32
2001-10-01	32
2002-01-01	31.9
2002-04-01	32.1
2002-07-01	32.6
2002-10-01	32.5
2003-01-01	32.3
2003-04-01	32.9
2003-07-01	33.1
2003-10-01	32.8
2004-01-01	34.1
2004-04-01	34.5
2004-07-01	34.5
2004-10-01	34.8
2005-01-01	34.2
2005-04-01	34.4
2005-07-01	33.9
2005-10-01	34.5
2006-01-01	34.5
2006-04-01	35.1
2006-07-01	34.7
2006-10-01	35.1
2007-01-01	34.5
2007-04-01	35
2007-07-01	35.1
2007-10-01	35.3
2008-01-01	35.2
2008-04-01	35.7
2008-07-01	35.4
2008-10-01	35.3
2009-01-01	34.7
2009-04-01	35.1
2009-07-01	34.5
2009-10-01	34.5
2010-01-01	34.2
2010-04-01	34.8
2010-07-01	34.3
2010-10-01	34.7
2011-01-01	34.7
2011-04-01	34.9
2011-07-01	34.4
2011-10-01	34.9
2012-01-01	34.8
2012-04-01	35.4
2012-07-01	34.9
2012-10-01	35
2013-01-01	34.5
2013-04-01	34.6
2013-07-01	34.3
2013-10-01	34.6
2014-01-01	34.3
2014-04-01	34.6
2014-07-01	34.6
2014-10-01	34.8
2015-01-01	34.5
2015-04-01	34.9
2015-07-01	34.7
2015-10-01	34.9
2016-01-01	34.7
2016-04-01	35.6
2016-07-01	35.4
2016-10-01	35.4
2017-01-01	35.3
2017-04-01	36.0
2017-07-01	36.0
2017-10-01	36.1
2018-01-01	35.8
2018-04-01	36.8