Quarter	Percent
1998-04-01	70.5
1999-01-01	72.6
1999-04-01	72.9
1999-07-01	72.2
1999-10-01	71.7
2000-01-01	72.4
2000-04-01	73.2
2000-07-01	73.2
2000-10-01	72.3
2001-01-01	71.7
2001-04-01	70.7
2001-07-01	70.1
2001-10-01	72.1
2002-01-01	72.2
2002-04-01	72
2002-07-01	72.9
2002-10-01	72.6
2003-01-01	73.1
2003-04-01	73.1
2003-07-01	73.2
2003-10-01	74.9
2004-01-01	73.9
2004-04-01	74.3
2004-07-01	74.8
2004-10-01	75.9
2005-01-01	76.9
2005-04-01	76.8
2005-07-01	77.1
2005-10-01	76.4
2006-01-01	76.2
2006-04-01	77
2006-07-01	77.1
2006-10-01	77.5
2007-01-01	77.8
2007-04-01	77.5
2007-07-01	77.7
2007-10-01	79.3
2008-01-01	79.4
2008-04-01	78.7
2008-07-01	79.2
2008-10-01	78.7
2009-01-01	80.5
2009-04-01	78.6
2009-07-01	78.7
2009-10-01	79.2
2010-01-01	81
2010-04-01	79.4
2010-07-01	79.7
2010-10-01	81.6
2011-01-01	77.8
2011-04-01	78.9
2011-07-01	79.2
2011-10-01	79
2012-01-01	78.6
2012-04-01	78.5
2012-07-01	79.4
2012-10-01	80
2013-01-01	79.4
2013-04-01	79.6
2013-07-01	80.6
2013-10-01	79.4
2014-01-01	80.5
2014-04-01	80.1
2014-07-01	80.9
2014-10-01	80.7
2015-01-01	81.0
2015-04-01	79.2
2015-07-01	80.1
2015-10-01	80.5
2016-01-01	79.5
2016-04-01	79.4
2016-07-01	79.5
2016-10-01	81.0
2017-01-01	79.7
2017-04-01	79.9
2017-07-01	78.9
2017-10-01	79.9
2018-01-01	79.8
2018-04-01	79.7