Quarter	Percent
2005-01-01	38.9
2005-04-01	38.9
2005-07-01	39.1
2005-10-01	39.3
2006-01-01	39.8
2006-04-01	39.8
2006-07-01	39.7
2006-10-01	40.7
2007-01-01	40.0
2007-04-01	39.1
2007-07-01	38.6
2007-10-01	40.2
2008-01-01	40.0
2008-04-01	39.5
2008-07-01	38.1
2008-10-01	38.2
2009-01-01	38.6
2009-04-01	37.9
2009-07-01	37.4
2009-10-01	38.1
2010-01-01	38.5
2010-04-01	38.0
2010-07-01	36.9
2010-10-01	36.5
2011-01-01	36.7
2011-04-01	36.0
2011-07-01	36.3
2011-10-01	36.8
2012-01-01	36.5
2012-04-01	35.6
2012-07-01	35.3
2012-10-01	36.0
2013-01-01	36.0
2013-04-01	35.3
2013-07-01	35.2
2013-10-01	35.1
2014-01-01	34.4
2014-04-01	34.3
2014-07-01	33.7
2014-10-01	34.3
2015-01-01	34.4
2015-04-01	33.7
2015-07-01	33.5
2015-10-01	33.3
2016-01-01	33.1
2016-04-01	32.1
2016-07-01	32.1
2016-10-01	32.3
2017-01-01	32.3
2017-04-01	31.6
2017-07-01	31.9
2017-10-01	31.9
2018-01-01	31.7
2018-04-01	31.1