Quarter	Percent
2000-04-01	39.9
2001-04-01	39.8
2002-04-01	39.5
2003-04-01	38.9
2004-04-01	38.5
2005-01-01	38.2
2005-04-01	37.8
2005-07-01	37.7
2005-10-01	37.5
2006-01-01	37.5
2006-04-01	37.2
2006-07-01	36.8
2006-10-01	37
2007-01-01	37.3
2007-04-01	37.0
2007-07-01	36.5
2007-10-01	36.6
2008-01-01	36.8
2008-04-01	36.4
2008-07-01	36.0
2008-10-01	36.1
2009-01-01	36.2
2009-04-01	35.9
2009-07-01	35.8
2009-10-01	35.8
2010-01-01	35.9
2010-04-01	35.6
2010-07-01	35.4
2010-10-01	35.5
2011-01-01	35.6
2011-04-01	35.3
2011-07-01	35.1
2011-10-01	34.9
2012-01-01	34.9
2012-04-01	34.5
2012-07-01	34.2
2012-10-01	34.1
2013-01-01	34.3
2013-04-01	34.0
2013-07-01	33.8
2013-10-01	33.7
2014-01-01	33.8
2014-04-01	33.6
2014-07-01	33.3
2014-10-01	33.2
2015-01-01	33.5
2015-04-01	33.2
2015-07-01	33.1
2015-10-01	33.0
2016-01-01	33.1
2016-04-01	32.7
2016-07-01	32.4
2016-10-01	32.5
2017-01-01	32.6
2017-04-01	32.2
2017-07-01	32.0
2017-10-01	32.0
2018-01-01	32.1
2018-04-01	31.8