Quarter	Percent
2006-01-01	19.1
2006-04-01	14.5
2006-07-01	15.7
2006-10-01	16.6
2007-01-01	18.5
2007-04-01	15.5
2007-07-01	17.3
2007-10-01	17.8
2008-01-01	19.3
2008-04-01	15.1
2008-07-01	17.7
2008-10-01	21.8
2009-01-01	25.2
2009-04-01	22.7
2009-07-01	21.3
2009-10-01	22.2
2010-01-01	23.3
2010-04-01	17.8
2010-07-01	19.2
2010-10-01	18.8
2011-01-01	18.6
2011-04-01	16.1
2011-07-01	17
2011-10-01	15.2
2012-01-01	16.6
2012-04-01	14.3
2012-07-01	15.1
2012-10-01	16.8
2013-01-01	18.3
2013-04-01	14.9
2013-07-01	16.8
2013-10-01	17.8
2014-01-01	17
2014-04-01	15.8
2014-07-01	18.7
2014-10-01	19.8
2015-01-01	20.0
2015-04-01	16.9
2015-07-01	18.2
2015-10-01	19.0
2016-01-01	18.6
2016-04-01	17.2
2016-07-01	19.8
2016-10-01	22.3
2017-01-01	23.1
2017-04-01	19.6
2017-07-01	20.4
2017-10-01	19.2
2018-01-01	18.9
2018-04-01	17.6