Quarter	Percent
1998-01-01	67.6
1998-04-01	66.9
1998-07-01	65.4
1998-10-01	64.4
1999-01-01	66.6
1999-04-01	66.2
1999-07-01	65.6
1999-10-01	65.7
2000-01-01	66.8
2000-04-01	66
2000-07-01	64.8
2000-10-01	65.2
2001-01-01	67.3
2001-04-01	67.5
2001-07-01	67.4
2001-10-01	67.3
2002-01-01	69
2002-04-01	69.1
2002-07-01	68.8
2002-10-01	69.1
2003-01-01	70.1
2003-04-01	69.9
2003-07-01	69.1
2003-10-01	71.5
2004-01-01	68.3
2004-04-01	68.1
2004-07-01	67.7
2004-10-01	68.9
2005-01-01	71.1
2005-04-01	71.9
2005-07-01	71.5
2005-10-01	70.5
2006-01-01	71.5
2006-04-01	73.9
2006-07-01	74.1
2006-10-01	73.1
2007-01-01	75.2
2007-04-01	74.9
2007-07-01	74.1
2007-10-01	74
2008-01-01	74
2008-04-01	74.5
2008-07-01	74.5
2008-10-01	74.9
2009-01-01	75.6
2009-04-01	76.4
2009-07-01	77.1
2009-10-01	76.2
2010-01-01	76.8
2010-04-01	77
2010-07-01	77.6
2010-10-01	76
2011-01-01	77.3
2011-04-01	78.1
2011-07-01	77.9
2011-10-01	75.6
2012-01-01	75.9
2012-04-01	76.6
2012-07-01	76.2
2012-10-01	75.3
2013-01-01	76.3
2013-04-01	77.3
2013-07-01	76.9
2013-10-01	75.9
2014-01-01	77.1
2014-04-01	77
2014-07-01	76.8
2014-10-01	76.7
2015-01-01	78.2
2015-04-01	78.4
2015-07-01	78.9
2015-10-01	77.8
2016-01-01	77.9
2016-04-01	77.0
2016-07-01	77.2
2016-10-01	76.9
2017-01-01	77.9
2017-04-01	78.0
2017-07-01	77.7
2017-10-01	78.0
2018-01-01	77.8
2018-04-01	78.3