Quarter	Percent
1998-04-01	55.8
1999-04-01	56.1
2000-04-01	55.8
2001-04-01	56.8
2002-04-01	57.5
2003-04-01	56.8
2004-04-01	56.3
2005-04-01	56.3
2006-04-01	56.9
2007-04-01	57.2
2008-04-01	58.9
2009-04-01	58.8
2010-01-01	56.7
2010-04-01	56.8
2010-07-01	56.9
2010-10-01	57.1
2011-01-01	57.4
2011-04-01	58.0
2011-07-01	57.2
2011-10-01	58.0
2012-01-01	58.0
2012-04-01	57.9
2012-07-01	58.2
2012-10-01	57.8
2013-01-01	57.8
2013-04-01	58.0
2013-07-01	58.2
2013-10-01	58.5
2014-01-01	58.0
2014-04-01	58.7
2014-07-01	58.6
2014-10-01	60.0
2015-01-01	59.4
2015-04-01	59.1
2015-07-01	58.8
2015-10-01	59.5
2016-01-01	59.9
2016-04-01	59.6
2016-07-01	59.3
2016-10-01	60.0
2017-01-01	59.6
2017-04-01	59.4
2017-07-01	59.1
2017-10-01	59.6
2018-01-01	59.6
2018-04-01	59.4