Quarter	Percent
1998-04-01	56.2
1998-10-01	54.8
1999-04-01	53.8
1999-10-01	55.0
2000-04-01	53.8
2000-10-01	54.1
2001-04-01	52.4
2001-10-01	53.6
2002-01-01	55.9
2002-04-01	58.3
2002-07-01	57.5
2002-10-01	56.2
2003-01-01	55.9
2003-04-01	52.3
2003-07-01	62.1
2003-10-01	52.1
2004-01-01	63.0
2004-04-01	55.0
2004-07-01	62.0
2004-10-01	57.3
2005-01-01	60.5
2005-04-01	58.5
2005-07-01	61.2
2005-10-01	60.1
2006-01-01	63.6
2006-04-01	63.6
2006-07-01	65.6
2006-10-01	64.5
2007-01-01	65.9
2007-04-01	64.9
2007-07-01	67.5
2007-10-01	72.1
2008-01-01	69.1
2008-04-01	68.7
2008-07-01	68.3
2008-10-01	66.6
2009-01-01	66.2
2009-04-01	68.6
2009-07-01	58.1
2009-10-01	58.2
2010-01-01	55.2
2010-04-01	63.2
2010-07-01	58.2
2010-10-01	57.4
2011-01-01	61.1
2011-04-01	63.2
2011-07-01	62.4
2011-10-01	63.5
2012-01-01	59.9
2012-04-01	65.0
2012-07-01	63.8
2012-10-01	64.0
2013-01-01	60.2
2013-04-01	62.8
2013-07-01	64.0
2013-10-01	61.9
2014-01-01	62.9
2014-04-01	64.0
2014-07-01	62.2
2014-10-01	65.7
2015-01-01	67.0
2015-04-01	66.3
2015-07-01	67.5
2015-10-01	71.2
2016-01-01	69.8
2016-04-01	68.8
2016-07-01	69.4
2016-10-01	69.7
2017-01-01	68.2
2017-04-01	68.5
2017-07-01	68.5
2017-10-01	71.2
2018-01-01	70.9
2018-04-01	73.9