Quarter	Percent
1999-01-01	60.5
2000-01-01	61.4
2001-01-01	60.8
2002-01-01	59
2003-01-01	59.3
2003-04-01	59.5
2003-07-01	55.0
2003-10-01	58.6
2004-01-01	59.9
2004-04-01	60.1
2004-07-01	54.3
2004-10-01	58.1
2005-01-01	59.6
2005-04-01	58.8
2005-07-01	55.3
2005-10-01	58.5
2006-01-01	60.0
2006-04-01	58.6
2006-07-01	54.9
2006-10-01	58.4
2007-01-01	59.5
2007-04-01	59.8
2007-07-01	55.0
2007-10-01	58.0
2008-01-01	59.0
2008-04-01	59.1
2008-07-01	55.3
2008-10-01	57.6
2009-01-01	57.6
2009-04-01	57.4
2009-07-01	56.0
2009-10-01	57.2
2010-01-01	57.7
2010-04-01	57.9
2010-07-01	55.9
2010-10-01	58.0
2011-01-01	59.2
2011-04-01	58.7
2011-07-01	57.2
2011-10-01	59.8
2012-01-01	60.2
2012-04-01	60.3
2012-07-01	57.3
2012-10-01	58.9
2013-01-01	59.3
2013-04-01	59.6
2013-07-01	57.8
2013-10-01	60.2
2014-01-01	60.3
2014-04-01	60.8
2014-07-01	59.0
2014-10-01	61.0
2015-01-01	60.3
2015-04-01	60.2
2015-07-01	58.9
2015-10-01	59.7
2016-01-01	60.0
2016-04-01	60.6
2016-07-01	60.0
2016-10-01	60.3
2017-01-01	61.4
2017-04-01	60.2
2017-07-01	57.7
2017-10-01	59.5
2018-01-01	59.8
2018-04-01	59.8