Quarter	Percent
1998-01-01	60.6
1998-04-01	60.5
1998-07-01	60.1
1998-10-01	60.1
1999-01-01	59
1999-04-01	58.9
1999-07-01	58.8
1999-10-01	58.9
2000-01-01	58.2
2000-04-01	58.4
2000-07-01	58.6
2000-10-01	58.6
2001-01-01	58.5
2001-04-01	58.5
2001-07-01	58.5
2001-10-01	58.7
2002-01-01	58.5
2002-04-01	59.1
2002-07-01	59.3
2002-10-01	59.3
2003-01-01	58.7
2003-04-01	58.7
2003-07-01	58.4
2003-10-01	58.2
2004-01-01	57.7
2004-04-01	58
2004-07-01	58.2
2004-10-01	58.3
2005-01-01	58.1
2005-04-01	58.7
2005-07-01	59.1
2005-10-01	59.1
2006-01-01	58.8
2006-04-01	59.2
2006-07-01	59.3
2006-10-01	59.4
2007-01-01	59.5
2007-04-01	60
2007-07-01	60.2
2007-10-01	60.4
2008-01-01	60.1
2008-04-01	60.4
2008-07-01	60.4
2008-10-01	60.5
2009-01-01	59.4
2009-04-01	59.2
2009-07-01	58.9
2009-10-01	58.9
2010-01-01	57.8
2010-04-01	58.4
2010-07-01	58.9
2010-10-01	58.9
2011-01-01	58.4
2011-04-01	58.9
2011-07-01	59.1
2011-10-01	58.9
2012-01-01	58.3
2012-04-01	59.1
2012-07-01	59.4
2012-10-01	59.4
2013-01-01	59.1
2013-04-01	60
2013-07-01	60.1
2013-10-01	60.2
2014-01-01	59.8
2014-04-01	60.3
2014-07-01	60.7
2014-10-01	61
2015-01-01	60.6
2015-04-01	61.3
2015-07-01	61.6
2015-10-01	61.9
2016-01-01	62.1
2016-04-01	62.6
2016-07-01	62.9
2016-10-01	63.3
2017-01-01	63.1
2017-04-01	63.5
2017-07-01	64.3
2017-10-01	64.5
2018-01-01	64.3
2018-04-01	64.9