Quarter	Percent
1998-04-01	81.7
1999-04-01	80.9
2000-04-01	79.3
2001-04-01	82.5
2002-04-01	78.9
2003-04-01	79.7
2004-04-01	79.1
2005-04-01	77.8
2006-04-01	77.1
2007-04-01	78.4
2008-04-01	78.9
2009-04-01	79.5
2010-01-01	77.9
2010-04-01	78.5
2010-07-01	78.4
2010-10-01	78.6
2011-01-01	79.0
2011-04-01	79.1
2011-07-01	79.4
2011-10-01	79.6
2012-01-01	78.6
2012-04-01	78.8
2012-07-01	80.2
2012-10-01	80.1
2013-01-01	79.7
2013-04-01	79.8
2013-07-01	79.7
2013-10-01	80.7
2014-01-01	79.0
2014-04-01	78.5
2014-07-01	78.3
2014-10-01	80.7
2015-01-01	81.3
2015-04-01	79.8
2015-07-01	79.1
2015-10-01	80.6
2016-01-01	79.0
2016-04-01	80.8
2016-07-01	81.6
2016-10-01	81.4
2017-01-01	80.7
2017-04-01	82.2
2017-07-01	82.0
2017-10-01	83.2
2018-01-01	81.7
2018-04-01	83.8