Quarter	Percent
1999-04-01	80.5
2000-01-01	79.2
2000-04-01	80.7
2000-07-01	80.9
2000-10-01	79.9
2001-01-01	79.1
2001-04-01	80.5
2001-07-01	80.6
2001-10-01	79.9
2002-01-01	79.3
2002-04-01	80.6
2002-07-01	80.4
2002-10-01	79.1
2003-01-01	78
2003-04-01	78.9
2003-07-01	79.4
2003-10-01	78.5
2004-01-01	77.4
2004-04-01	78.7
2004-07-01	79.3
2004-10-01	78.4
2005-01-01	77.3
2005-04-01	78.3
2005-07-01	79.1
2005-10-01	78.6
2006-01-01	77.6
2006-04-01	78.4
2006-07-01	78.5
2006-10-01	77.6
2007-01-01	77.8
2007-04-01	78.8
2007-07-01	79.2
2007-10-01	79.3
2008-01-01	79.6
2008-04-01	80.6
2008-07-01	80.5
2008-10-01	79.5
2009-01-01	79.1
2009-04-01	79.7
2009-07-01	78.8
2009-10-01	77.9
2010-01-01	77.9
2010-04-01	78.8
2010-07-01	78.1
2010-10-01	77.7
2011-01-01	77.2
2011-04-01	78
2011-07-01	78.3
2011-10-01	77.8
2012-01-01	77.9
2012-04-01	78.8
2012-07-01	78.5
2012-10-01	77.9
2013-01-01	77.8
2013-04-01	78.5
2013-07-01	78.6
2013-10-01	77.8
2014-01-01	77.4
2014-04-01	78.3
2014-07-01	78.4
2014-10-01	77.9
2015-01-01	77.7
2015-04-01	78.7
2015-07-01	78.8
2015-10-01	77.7
2016-01-01	78.1
2016-04-01	78.2
2016-07-01	78.6
2016-10-01	77.3
2017-01-01	77.0
2017-04-01	77.7
2017-07-01	77.7
2017-10-01	76.9
2018-01-01	77.2
2018-04-01	78.1