Quarter	Percent
1998-01-01	76.1
1998-04-01	76.1
1998-07-01	76.0
1998-10-01	75.6
1999-01-01	74.1
1999-04-01	74
1999-07-01	74.1
1999-10-01	73.8
2000-01-01	72.7
2000-04-01	73.1
2000-07-01	73.4
2000-10-01	73.4
2001-01-01	72.9
2001-04-01	73.1
2001-07-01	73.2
2001-10-01	73.5
2002-01-01	73.2
2002-04-01	73.9
2002-07-01	74.2
2002-10-01	74.2
2003-01-01	73.3
2003-04-01	73.2
2003-07-01	73.1
2003-10-01	72.8
2004-01-01	71.7
2004-04-01	72.1
2004-07-01	72.7
2004-10-01	72.8
2005-01-01	72.4
2005-04-01	73.3
2005-07-01	73.8
2005-10-01	73.6
2006-01-01	73
2006-04-01	73.6
2006-07-01	73.9
2006-10-01	74.2
2007-01-01	74.1
2007-04-01	74.5
2007-07-01	75.2
2007-10-01	75.5
2008-01-01	74.9
2008-04-01	75.3
2008-07-01	75.7
2008-10-01	75.8
2009-01-01	74.2
2009-04-01	73.9
2009-07-01	73.7
2009-10-01	73.6
2010-01-01	72.3
2010-04-01	73.5
2010-07-01	74.3
2010-10-01	74
2011-01-01	73.1
2011-04-01	74.1
2011-07-01	74.6
2011-10-01	74.3
2012-01-01	73.6
2012-04-01	74.6
2012-07-01	75.3
2012-10-01	75
2013-01-01	74.6
2013-04-01	75.8
2013-07-01	76.1
2013-10-01	76.1
2014-01-01	76
2014-04-01	76.9
2014-07-01	77.6
2014-10-01	77.5
2015-01-01	76.9
2015-04-01	77.8
2015-07-01	78.2
2015-10-01	78.6
2016-01-01	78.5
2016-04-01	79.0
2016-07-01	79.7
2016-10-01	80.0
2017-01-01	80.0
2017-04-01	80.6
2017-07-01	81.4
2017-10-01	81.5
2018-01-01	81.2
2018-04-01	81.7