Quarter	Percent
1999-01-01	81.2
1999-04-01	81.2
1999-07-01	81.5
1999-10-01	82.2
2000-01-01	82.7
2000-04-01	82.5
2000-07-01	82.9
2000-10-01	83.4
2001-01-01	83.8
2001-04-01	83.8
2001-07-01	84
2001-10-01	84.1
2002-01-01	83.5
2002-04-01	83.7
2002-07-01	84.2
2002-10-01	84.1
2003-01-01	84.4
2003-04-01	84.6
2003-07-01	85.1
2003-10-01	85.2
2004-01-01	84.5
2004-04-01	84.3
2004-07-01	84.1
2004-10-01	83.5
2005-01-01	83
2005-04-01	82.1
2005-07-01	81.6
2005-10-01	81.8
2006-01-01	81.2
2006-04-01	81.3
2006-07-01	81.2
2006-10-01	81.1
2007-01-01	80.8
2007-04-01	80.4
2007-07-01	80.2
2007-10-01	81.3
2008-01-01	81.6
2008-04-01	81.9
2008-07-01	82.9
2008-10-01	82.1
2009-01-01	80.9
2009-04-01	80.6
2009-07-01	80.6
2009-10-01	80.9
2010-01-01	80.7
2010-04-01	80.6
2010-07-01	81.1
2010-10-01	81.1
2011-01-01	80.5
2011-04-01	80.1
2011-07-01	80.6
2011-10-01	80.4
2012-01-01	80.8
2012-04-01	80.5
2012-07-01	80.5
2012-10-01	79.7
2013-01-01	80.4
2013-04-01	80
2013-07-01	80.8
2013-10-01	80.9
2014-01-01	80.9
2014-04-01	80.4
2014-07-01	79.9
2014-10-01	80.3
2015-01-01	80.5
2015-04-01	80.4
2015-07-01	80.7
2015-10-01	81.5
2016-01-01	82.1
2016-04-01	81.9
2016-07-01	81.4
2016-10-01	80.4
2017-01-01	80.3
2017-04-01	79.3
2017-07-01	80.2
2017-10-01	79.4
2018-01-01	79.9
2018-04-01	79.1