Quarter	Percent
1998-01-01	61.0
1998-04-01	61.8
1998-07-01	61.4
1998-10-01	61.6
1999-01-01	61.6
1999-04-01	61.9
1999-07-01	62.1
1999-10-01	62.1
2000-01-01	62.4
2000-04-01	62.6
2000-07-01	63
2000-10-01	63.1
2001-01-01	63.3
2001-04-01	63.4
2001-07-01	63.5
2001-10-01	63.5
2002-01-01	63.4
2002-04-01	63.5
2002-07-01	63.5
2002-10-01	62.5
2003-01-01	62.5
2003-04-01	62.5
2003-07-01	62.6
2003-10-01	62.2
2004-01-01	62.1
2004-04-01	62.2
2004-07-01	62
2004-10-01	61.9
2005-01-01	61.6
2005-04-01	61.9
2005-07-01	61.8
2005-10-01	61.7
2006-01-01	61.8
2006-04-01	62.3
2006-07-01	62.3
2006-10-01	61.7
2007-01-01	61.7
2007-04-01	61.9
2007-07-01	62.4
2007-10-01	62.3
2008-01-01	62.3
2008-04-01	62.8
2008-07-01	62.3
2008-10-01	62
2009-01-01	61.2
2009-04-01	60.9
2009-07-01	60.1
2009-10-01	60.1
2010-01-01	60.1
2010-04-01	59.9
2010-07-01	59.5
2010-10-01	59.3
2011-01-01	58.4
2011-04-01	58.8
2011-07-01	58.3
2011-10-01	56.9
2012-01-01	56.4
2012-04-01	56.6
2012-07-01	56.1
2012-10-01	54.8
2013-01-01	53.9
2013-04-01	54.8
2013-07-01	55.5
2013-10-01	55.7
2014-01-01	55.4
2014-04-01	56.4
2014-07-01	57
2014-10-01	56.5
2015-01-01	56.3
2015-04-01	57.6
2015-07-01	57.6
2015-10-01	57.5
2016-01-01	57.0
2016-04-01	58.2
2016-07-01	58.9
2016-10-01	58.7
2017-01-01	59.0
2017-04-01	60.2
2017-07-01	60.8
2017-10-01	61.0
2018-01-01	61.0
2018-04-01	61.9