Quarter	Percent
1999-01-01	59.9
1999-04-01	60.5
1999-07-01	60.6
1999-10-01	61.7
2000-01-01	62.5
2000-04-01	62.7
2000-07-01	62.8
2000-10-01	63.4
2001-01-01	61.1
2001-04-01	60.9
2001-07-01	61.1
2001-10-01	62
2002-01-01	63.9
2002-04-01	64.7
2002-07-01	65
2002-10-01	65.6
2003-01-01	66.5
2003-04-01	66.9
2003-07-01	67.2
2003-10-01	68.2
2004-01-01	68.4
2004-04-01	68.8
2004-07-01	68.9
2004-10-01	70.2
2005-01-01	69.5
2005-04-01	69.9
2005-07-01	69.2
2005-10-01	70.6
2006-01-01	71.1
2006-04-01	71.7
2006-07-01	71.4
2006-10-01	72.8
2007-01-01	73.1
2007-04-01	73.1
2007-07-01	72.9
2007-10-01	74.1
2008-01-01	74.6
2008-04-01	75
2008-07-01	74.8
2008-10-01	76.6
2009-01-01	77.1
2009-04-01	77.1
2009-07-01	76.7
2009-10-01	77.8
2010-01-01	78.4
2010-04-01	78.8
2010-07-01	78.4
2010-10-01	79.4
2011-01-01	79.6
2011-04-01	80
2011-07-01	79.2
2011-10-01	80.1
2012-01-01	81.1
2012-04-01	80.8
2012-07-01	80.7
2012-10-01	81.7
2013-01-01	81.9
2013-04-01	81.9
2013-07-01	81.3
2013-10-01	82.1
2014-01-01	82.1
2014-04-01	82.2
2014-07-01	81.3
2014-10-01	82.4
2015-01-01	82.1
2015-04-01	82.6
2015-07-01	81.1
2015-10-01	82.3
2016-01-01	82.3
2016-04-01	82.7
2016-07-01	81.9
2016-10-01	82.4
2017-01-01	82.3
2017-04-01	82.0
2017-07-01	81.5
2017-10-01	82.2
2018-01-01	81.9
2018-04-01	82.2
2018-07-01	81.3