Quarter	Percent
2005-01-01	40.5
2005-04-01	39.8
2005-07-01	39.6
2005-10-01	39.7
2006-01-01	40.0
2006-04-01	39.4
2006-07-01	39.1
2006-10-01	39.2
2007-01-01	39.7
2007-04-01	39.2
2007-07-01	39.0
2007-10-01	38.9
2008-01-01	39.3
2008-04-01	38.6
2008-07-01	38.6
2008-10-01	38.7
2009-01-01	39.0
2009-04-01	38.4
2009-07-01	38.2
2009-10-01	38.5
2010-01-01	38.9
2010-04-01	38.3
2010-07-01	38.2
2010-10-01	38.6
2011-01-01	38.8
2011-04-01	38.1
2011-07-01	38.1
2011-10-01	38.1
2012-01-01	38.5
2012-04-01	37.7
2012-07-01	37.7
2012-10-01	37.7
2013-01-01	38.0
2013-04-01	37.4
2013-07-01	37.4
2013-10-01	37.4
2014-01-01	37.7
2014-04-01	37.2
2014-07-01	37.2
2014-10-01	37.1
2015-01-01	37.5
2015-04-01	37.0
2015-07-01	36.9
2015-10-01	36.8
2016-01-01	37.0
2016-04-01	36.5
2016-07-01	36.3
2016-10-01	36.4
2017-01-01	36.5
2017-04-01	36.0