Quarter	Percent
2005-01-01	35.9
2005-04-01	34.9
2005-07-01	37.1
2005-10-01	35.2
2006-01-01	38.6
2006-04-01	40.6
2006-07-01	39.9
2006-10-01	41.8
2007-01-01	37.8
2007-04-01	36.3
2007-07-01	34.2
2007-10-01	38.6
2008-01-01	38.4
2008-04-01	36.7
2008-07-01	38.3
2008-10-01	35.0
2009-01-01	34.6
2009-04-01	35.3
2009-07-01	36.2
2009-10-01	40.5
2010-01-01	37.8
2010-04-01	35.8
2010-07-01	37.8
2010-10-01	38.2
2011-01-01	36.5
2011-04-01	36.4
2011-07-01	35.1
2011-10-01	34.8
2012-01-01	36.0
2012-04-01	36.5
2012-07-01	33.6
2012-10-01	35.7
2013-01-01	35.9
2013-04-01	36.1
2013-07-01	34.9
2013-10-01	32.2
2014-01-01	31.1
2014-04-01	32.9
2014-07-01	31.4
2014-10-01	31.9
2015-01-01	32.4
2015-04-01	29.2
2015-07-01	29.3
2015-10-01	29.8
2016-01-01	28.3
2016-04-01	24.8
2016-07-01	25.1
2016-10-01	27.4
2017-01-01	27.9
2017-04-01	26.9
2017-07-01	27.0
2017-10-01	25.0
2018-01-01	23.8
2018-04-01	23.6