Quarter	Percent
1998-01-01	84.1
1998-04-01	84.0
1998-07-01	83.5
1998-10-01	83.2
1999-01-01	82.1
1999-04-01	82
1999-07-01	81.8
1999-10-01	81.8
2000-01-01	81
2000-04-01	81.5
2000-07-01	81.8
2000-10-01	82
2001-01-01	82
2001-04-01	82
2001-07-01	82.1
2001-10-01	82.3
2002-01-01	82
2002-04-01	82.6
2002-07-01	82.7
2002-10-01	82.7
2003-01-01	82
2003-04-01	81.9
2003-07-01	81.4
2003-10-01	81.4
2004-01-01	80.7
2004-04-01	81.4
2004-07-01	81.7
2004-10-01	81.8
2005-01-01	81.2
2005-04-01	82.1
2005-07-01	82.4
2005-10-01	82.3
2006-01-01	82
2006-04-01	82.6
2006-07-01	82.7
2006-10-01	82.9
2007-01-01	82.8
2007-04-01	83.5
2007-07-01	83.6
2007-10-01	83.9
2008-01-01	83.6
2008-04-01	84
2008-07-01	84
2008-10-01	83.8
2009-01-01	82.5
2009-04-01	82.5
2009-07-01	82.3
2009-10-01	82.7
2010-01-01	81.3
2010-04-01	82.3
2010-07-01	82.5
2010-10-01	82.5
2011-01-01	82
2011-04-01	82.8
2011-07-01	83.1
2011-10-01	83.4
2012-01-01	82.4
2012-04-01	83.1
2012-07-01	83.2
2012-10-01	83.2
2013-01-01	82.8
2013-04-01	83.8
2013-07-01	83.6
2013-10-01	83.8
2014-01-01	83.3
2014-04-01	83.7
2014-07-01	84
2014-10-01	84.3
2015-01-01	83.8
2015-04-01	84.5
2015-07-01	84.7
2015-10-01	85.0
2016-01-01	85.1
2016-04-01	85.6
2016-07-01	85.8
2016-10-01	86.4
2017-01-01	85.9
2017-04-01	86.5
2017-07-01	87.1
2017-10-01	87.2
2018-01-01	86.9
2018-04-01	87.5