Quarter	Percent
1998-04-01	67.2
1999-04-01	69.4
2000-04-01	68.4
2001-01-01	69.5
2001-04-01	69.3
2001-07-01	70.3
2001-10-01	70.8
2002-01-01	71
2002-04-01	71.3
2002-07-01	71.3
2002-10-01	71.4
2003-01-01	71.4
2003-04-01	71.8
2003-07-01	72.2
2003-10-01	72.3
2004-01-01	72.4
2004-04-01	72.6
2004-07-01	73
2004-10-01	72.8
2005-01-01	73
2005-04-01	71.9
2005-07-01	72.7
2005-10-01	73.3
2006-01-01	73.6
2006-04-01	72.8
2006-07-01	72.4
2006-10-01	72.6
2007-01-01	72.6
2007-04-01	72.9
2007-07-01	73.1
2007-10-01	72.8
2008-01-01	72.4
2008-04-01	72.5
2008-07-01	73
2008-10-01	73.2
2009-01-01	73.7
2009-04-01	73.4
2009-07-01	73.9
2009-10-01	74.5
2010-01-01	74.4
2010-04-01	74.4
2010-07-01	74.9
2010-10-01	75.3
2011-01-01	75.6
2011-04-01	76.1
2011-07-01	75.9
2011-10-01	76.3
2012-01-01	76.3
2012-04-01	77
2012-07-01	76.9
2012-10-01	77.7
2013-01-01	77.2
2013-04-01	77.3
2013-07-01	77.6
2013-10-01	78
2014-01-01	77.9
2014-04-01	78.4
2014-07-01	78.2
2014-10-01	78.3
2015-01-01	78.5
2015-04-01	78.6
2015-07-01	78.4
2015-10-01	79.1
2016-01-01	79.1
2016-04-01	79.5
2016-07-01	80.2
2016-10-01	80.0
2017-01-01	80.3
2017-04-01	80.9
2017-07-01	80.6
2017-10-01	80.2
2018-01-01	80.9
2018-04-01	81.4