Quarter	Percent
1998-01-01	55.3
1998-04-01	56
1998-07-01	55.5
1998-10-01	56.3
1999-01-01	58
1999-04-01	58.2
1999-07-01	58
1999-10-01	57.5
2000-01-01	58.3
2000-04-01	58.3
2000-07-01	58.3
2000-10-01	58.3
2001-01-01	62.1
2001-04-01	61.2
2001-07-01	60.2
2001-10-01	60.8
2002-01-01	60.8
2002-04-01	60.7
2002-07-01	61.2
2002-10-01	61.9
2003-01-01	61
2003-04-01	61.6
2003-07-01	63
2003-10-01	64.3
2004-01-01	58.7
2004-04-01	59.7
2004-07-01	61.3
2004-10-01	61.5
2005-01-01	61.8
2005-04-01	63.1
2005-07-01	63.8
2005-10-01	63.7
2006-01-01	62.8
2006-04-01	63.8
2006-07-01	64.9
2006-10-01	65.6
2007-01-01	64.8
2007-04-01	65.8
2007-07-01	65.3
2007-10-01	66.3
2008-01-01	66.6
2008-04-01	66.2
2008-07-01	65.3
2008-10-01	65.9
2009-01-01	65.7
2009-04-01	66.4
2009-07-01	65.4
2009-10-01	66.8
2010-01-01	66.9
2010-04-01	66.8
2010-07-01	66.7
2010-10-01	67.5
2011-01-01	68.4
2011-04-01	68.8
2011-07-01	67.7
2011-10-01	68.4
2012-01-01	68.6
2012-04-01	69
2012-07-01	68.9
2012-10-01	68.5
2013-01-01	68.2
2013-04-01	68.7
2013-07-01	68
2013-10-01	68.8
2014-01-01	70.3
2014-04-01	70.3
2014-07-01	69.3
2014-10-01	70.2
2015-01-01	70.8
2015-04-01	72.2
2015-07-01	72.7
2015-10-01	73.7
2016-01-01	73.9
2016-04-01	73.7
2016-07-01	72.9
2016-10-01	73.8
2017-01-01	73.7
2017-04-01	73.5
2017-07-01	73.1
2017-10-01	75.0
2018-01-01	74.8
2018-04-01	74.8