Quarter	Percent
2005-01-01	58.4
2005-04-01	53.9
2005-07-01	53.0
2005-10-01	55.4
2006-01-01	51.6
2006-04-01	51.0
2006-07-01	53.7
2006-10-01	53.2
2007-01-01	50.1
2007-04-01	50.3
2007-07-01	49.8
2007-10-01	53.2
2008-01-01	52.1
2008-04-01	50.1
2008-07-01	48.4
2008-10-01	50.7
2009-01-01	48.6
2009-04-01	46.9
2009-07-01	47.3
2009-10-01	47.4
2010-01-01	48.4
2010-04-01	48.2
2010-07-01	49.0
2010-10-01	47.4
2011-01-01	46.9
2011-04-01	46.4
2011-07-01	47.1
2011-10-01	47.4
2012-01-01	46.3
2012-04-01	45.8
2012-07-01	45.1
2012-10-01	46.0
2013-01-01	44.3
2013-04-01	44.3
2013-07-01	44.3
2013-10-01	42.6
2014-01-01	41.8
2014-04-01	42.4
2014-07-01	40.1
2014-10-01	39.9
2015-01-01	38.1
2015-04-01	36.8
2015-07-01	37.1
2015-10-01	34.6
2016-01-01	33.0
2016-04-01	33.5
2016-07-01	33.5
2016-10-01	31.2
2017-01-01	30.5
2017-04-01	30.2
2017-07-01	31.4
2017-10-01	29.4
2018-01-01	28.4
2018-04-01	29.0