Quarter	Percent
1999-01-01	76.6
1999-04-01	75.9
1999-07-01	76.1
1999-10-01	75.8
2000-01-01	74.3
2000-04-01	74.2
2000-07-01	74.9
2000-10-01	75.5
2001-01-01	74.1
2001-04-01	74.6
2001-07-01	75.2
2001-10-01	75.4
2002-01-01	74.2
2002-04-01	74.8
2002-07-01	75.5
2002-10-01	75.6
2003-01-01	75
2003-04-01	76.3
2003-07-01	76.8
2003-10-01	76
2004-01-01	73.6
2004-04-01	74.4
2004-07-01	75.3
2004-10-01	75.2
2005-01-01	74.5
2005-04-01	74.9
2005-07-01	75.6
2005-10-01	76
2006-01-01	75.9
2006-04-01	77.1
2006-07-01	77.8
2006-10-01	78
2007-01-01	77.6
2007-04-01	77.7
2007-07-01	77.9
2007-10-01	78.9
2008-01-01	78.7
2008-04-01	79.5
2008-07-01	81.2
2008-10-01	81.1
2009-01-01	79
2009-04-01	78.2
2009-07-01	77.4
2009-10-01	76.5
2010-01-01	74.9
2010-04-01	75.4
2010-07-01	76.2
2010-10-01	76.7
2011-01-01	76
2011-04-01	76.6
2011-07-01	77
2011-10-01	76.4
2012-01-01	76.5
2012-04-01	76.5
2012-07-01	76.8
2012-10-01	75.7
2013-01-01	75.7
2013-04-01	75.9
2013-07-01	76.2
2013-10-01	76.2
2014-01-01	76.4
2014-04-01	76.7
2014-07-01	76.9
2014-10-01	77.2
2015-01-01	77.1
2015-04-01	78.1
2015-07-01	78.4
2015-10-01	79.0
2016-01-01	79.6
2016-04-01	80.4
2016-07-01	80.1
2016-10-01	79.9
2017-01-01	79.7
2017-04-01	79.9
2017-07-01	80.4
2017-10-01	80.0
2018-01-01	80.8
2018-04-01	80.8