Quarter	Percent
1998-01-01	64
1998-04-01	64.7
1998-07-01	65.1
1998-10-01	64.4
1999-01-01	63.9
1999-04-01	64
1999-07-01	63.8
1999-10-01	63.2
2000-01-01	63.4
2000-04-01	64
2000-07-01	64.2
2000-10-01	63.8
2001-01-01	63.3
2001-04-01	63.7
2001-07-01	63.8
2001-10-01	63.1
2002-01-01	63
2002-04-01	64.2
2002-07-01	64.5
2002-10-01	64.2
2003-01-01	64.5
2003-04-01	64.9
2003-07-01	65.2
2003-10-01	64.7
2004-01-01	64.2
2004-04-01	65.1
2004-07-01	65.1
2004-10-01	64.8
2005-01-01	64.9
2005-04-01	65.5
2005-07-01	65.4
2005-10-01	65.3
2006-01-01	65.5
2006-04-01	65.9
2006-07-01	66.3
2006-10-01	66
2007-01-01	65.8
2007-04-01	66.3
2007-07-01	66.7
2007-10-01	66.4
2008-01-01	66.2
2008-04-01	66.9
2008-07-01	66.9
2008-10-01	66.2
2009-01-01	65.3
2009-04-01	65.7
2009-07-01	65.8
2009-10-01	64.7
2010-01-01	63.9
2010-04-01	63.5
2010-07-01	63.1
2010-10-01	61.5
2011-01-01	59.9
2011-04-01	59.5
2011-07-01	58.3
2011-10-01	55.8
2012-01-01	54.6
2012-04-01	53.8
2012-07-01	53.2
2012-10-01	52.1
2013-01-01	51
2013-04-01	51.6
2013-07-01	51.8
2013-10-01	51
2014-01-01	50.7
2014-04-01	51.5
2014-07-01	52.1
2014-10-01	51.2
2015-01-01	51.0
2015-04-01	52.4
2015-07-01	53.4
2015-10-01	53.0
2016-01-01	52.8
2016-04-01	54.2
2016-07-01	54.7
2016-10-01	53.7
2017-01-01	53.9
2017-04-01	55.6
2017-07-01	56.6
2017-10-01	55.6
2018-01-01	55.6
2018-04-01	57.3