Quarter	Percent
1998-01-01	29.6
1998-04-01	29.7
1998-07-01	29.4
1998-10-01	29.3
1999-01-01	29.8
1999-04-01	29.9
1999-07-01	29.8
1999-10-01	29.7
2000-01-01	30.3
2000-04-01	30.7
2000-07-01	30.5
2000-10-01	30.7
2001-01-01	31
2001-04-01	31.1
2001-07-01	30.9
2001-10-01	30.9
2002-01-01	31.3
2002-04-01	31.1
2002-07-01	30.8
2002-10-01	30.9
2003-01-01	31.5
2003-04-01	31.7
2003-07-01	31.5
2003-10-01	31.6
2004-01-01	31.9
2004-04-01	31.9
2004-07-01	31.5
2004-10-01	31.4
2005-01-01	31.4
2005-04-01	31.5
2005-07-01	31
2005-10-01	31.3
2006-01-01	31.4
2006-04-01	31.6
2006-07-01	31.4
2006-10-01	31.5
2007-01-01	31.9
2007-04-01	31.9
2007-07-01	31.4
2007-10-01	31.5
2008-01-01	32
2008-04-01	31.9
2008-07-01	31.7
2008-10-01	31.6
2009-01-01	31.9
2009-04-01	31.8
2009-07-01	31.5
2009-10-01	31.6
2010-01-01	32.2
2010-04-01	32.1
2010-07-01	31.6
2010-10-01	31.9
2011-01-01	32.7
2011-04-01	32.3
2011-07-01	32.3
2011-10-01	32.6
2012-01-01	32.8
2012-04-01	32.5
2012-07-01	31.9
2012-10-01	32
2013-01-01	32.2
2013-04-01	32
2013-07-01	31.7
2013-10-01	31.9
2014-01-01	32
2014-04-01	31.9
2014-07-01	31.6
2014-10-01	31.7
2015-01-01	32.1
2015-04-01	32.1
2015-07-01	31.9
2015-10-01	31.8
2016-01-01	31.9
2016-04-01	31.7
2016-07-01	31.4
2016-10-01	31.5
2017-01-01	31.8
2017-04-01	31.6
2017-07-01	31.1
2017-10-01	31.3
2018-01-01	31.5
2018-04-01	31.3