Quarter	Percent
2006-01-01	78.7
2006-04-01	76.7
2006-07-01	75.1
2006-10-01	75.9
2007-01-01	77.7
2007-04-01	75.9
2007-07-01	75
2007-10-01	77.5
2008-01-01	77.9
2008-04-01	75.8
2008-07-01	73.6
2008-10-01	75.2
2009-01-01	77.4
2009-04-01	75.5
2009-07-01	72.5
2009-10-01	75
2010-01-01	76
2010-04-01	74.9
2010-07-01	72.4
2010-10-01	74.6
2011-01-01	75.8
2011-04-01	73.7
2011-07-01	71.7
2011-10-01	74.1
2012-01-01	76.4
2012-04-01	74.5
2012-07-01	74.2
2012-10-01	74
2013-01-01	74.5
2013-04-01	72.8
2013-07-01	71.5
2013-10-01	74
2014-01-01	74.5
2014-04-01	72.1
2014-07-01	70.8
2014-10-01	72
2015-01-01	72.9
2015-04-01	70.2
2015-07-01	68.0
2015-10-01	70.7
2016-01-01	71.8
2016-04-01	69.8
2016-07-01	67.3
2016-10-01	69.7
2017-01-01	71.3
2017-04-01	69.0
2017-07-01	66.8
2017-10-01	69.0
2018-01-01	70.7
2018-04-01	69.1