Quarter	Percent
1999-01-01	34.2
2000-01-01	34.1
2000-04-01	33.9
2000-07-01	34.2
2000-10-01	34.7
2001-01-01	34.5
2001-04-01	34
2001-07-01	34.2
2001-10-01	35.2
2002-01-01	35.4
2002-04-01	35.1
2002-07-01	35.2
2002-10-01	35.9
2003-01-01	36.4
2003-04-01	36
2003-07-01	35.7
2003-10-01	36.1
2004-01-01	36
2004-04-01	36.3
2004-07-01	35.9
2004-10-01	35.9
2005-01-01	36.3
2005-04-01	36.1
2005-07-01	34.8
2005-10-01	35.4
2006-01-01	37.2
2006-04-01	37.1
2006-07-01	35.9
2006-10-01	36.4
2007-01-01	37.4
2007-04-01	37.1
2007-07-01	36.4
2007-10-01	36.4
2008-01-01	36.8
2008-04-01	36.5
2008-07-01	35.7
2008-10-01	35.7
2009-01-01	35.8
2009-04-01	35.6
2009-07-01	34.8
2009-10-01	35.1
2010-01-01	35.2
2010-04-01	34.7
2010-07-01	34.2
2010-10-01	34.6
2011-01-01	34.9
2011-04-01	34.4
2011-07-01	33.9
2011-10-01	33.9
2012-01-01	34.2
2012-04-01	33.6
2012-07-01	33.1
2012-10-01	33.2
2013-01-01	33.7
2013-04-01	33.2
2013-07-01	32.6
2013-10-01	32.6
2014-01-01	32.5
2014-04-01	32.4
2014-07-01	31.8
2014-10-01	31.8
2015-01-01	32.1
2015-04-01	32.4
2015-07-01	31.6
2015-10-01	31.5
2016-01-01	31.5
2016-04-01	31.4
2016-07-01	30.9
2016-10-01	31.0
2017-01-01	30.9
2017-04-01	30.3
2017-07-01	30.1
2017-10-01	30.5
2018-01-01	30.5
2018-04-01	29.8