Quarter	Percent
2006-01-01	28.8
2006-04-01	26.4
2006-07-01	25.1
2006-10-01	26.4
2007-01-01	28.6
2007-04-01	26.1
2007-07-01	24.8
2007-10-01	26.8
2008-01-01	28.3
2008-04-01	25.8
2008-07-01	24.7
2008-10-01	25.9
2009-01-01	27.9
2009-04-01	26
2009-07-01	24.3
2009-10-01	25.7
2010-01-01	26.7
2010-04-01	24.9
2010-07-01	24.4
2010-10-01	25.8
2011-01-01	25.7
2011-04-01	24
2011-07-01	23
2011-10-01	24.8
2012-01-01	27.2
2012-04-01	24.7
2012-07-01	23.9
2012-10-01	24.2
2013-01-01	25.9
2013-04-01	23.8
2013-07-01	23.3
2013-10-01	24.7
2014-01-01	24.8
2014-04-01	22.9
2014-07-01	22.5
2014-10-01	23.7
2015-01-01	24.2
2015-04-01	22.8
2015-07-01	21.7
2015-10-01	23.2
2016-01-01	23.6
2016-04-01	21.9
2016-07-01	21.7
2016-10-01	22.5
2017-01-01	22.8
2017-04-01	21.7
2017-07-01	20.7
2017-10-01	22.1
2018-01-01	22.9
2018-04-01	21.6