Quarter	Percent
2006-01-01	71.2
2006-04-01	73.6
2006-07-01	74.9
2006-10-01	73.6
2007-01-01	71.4
2007-04-01	73.9
2007-07-01	75.2
2007-10-01	73.2
2008-01-01	71.7
2008-04-01	74.2
2008-07-01	75.3
2008-10-01	74.1
2009-01-01	72.1
2009-04-01	74
2009-07-01	75.7
2009-10-01	74.3
2010-01-01	73.3
2010-04-01	75.1
2010-07-01	75.6
2010-10-01	74.2
2011-01-01	74.3
2011-04-01	76
2011-07-01	77
2011-10-01	75.2
2012-01-01	72.8
2012-04-01	75.3
2012-07-01	76.1
2012-10-01	75.8
2013-01-01	74.1
2013-04-01	76.2
2013-07-01	76.7
2013-10-01	75.3
2014-01-01	75.2
2014-04-01	77.1
2014-07-01	77.5
2014-10-01	76.3
2015-01-01	75.8
2015-04-01	77.2
2015-07-01	78.3
2015-10-01	76.8
2016-01-01	76.4
2016-04-01	78.1
2016-07-01	78.3
2016-10-01	77.5
2017-01-01	77.2
2017-04-01	78.3
2017-07-01	79.3
2017-10-01	77.9
2018-01-01	77.1
2018-04-01	78.4