Quarter	Percent
1998-01-01	51.8
1998-04-01	51.5
1998-07-01	51.0
1998-10-01	51.1
1999-01-01	50.5
1999-04-01	50.4
1999-07-01	50.1
1999-10-01	50.5
2000-01-01	50
2000-04-01	50
2000-07-01	50.1
2000-10-01	50.2
2001-01-01	50.4
2001-04-01	50.2
2001-07-01	50
2001-10-01	50
2002-01-01	50
2002-04-01	50.6
2002-07-01	50.6
2002-10-01	50.7
2003-01-01	50.2
2003-04-01	50.2
2003-07-01	49.7
2003-10-01	49.7
2004-01-01	49.5
2004-04-01	49.7
2004-07-01	49.7
2004-10-01	49.8
2005-01-01	49.7
2005-04-01	50
2005-07-01	50.3
2005-10-01	50.5
2006-01-01	50.4
2006-04-01	50.6
2006-07-01	50.6
2006-10-01	50.7
2007-01-01	50.7
2007-04-01	51.3
2007-07-01	51.2
2007-10-01	51.3
2008-01-01	51.1
2008-04-01	51.6
2008-07-01	51.3
2008-10-01	51.3
2009-01-01	50.6
2009-04-01	50.4
2009-07-01	50.2
2009-10-01	50.2
2010-01-01	49.3
2010-04-01	49.6
2010-07-01	49.8
2010-10-01	50.2
2011-01-01	50
2011-04-01	50.4
2011-07-01	50.5
2011-10-01	50.5
2012-01-01	50.1
2012-04-01	50.7
2012-07-01	50.9
2012-10-01	51.2
2013-01-01	51.1
2013-04-01	51.8
2013-07-01	51.8
2013-10-01	52
2014-01-01	51.6
2014-04-01	51.8
2014-07-01	52.2
2014-10-01	52.9
2015-01-01	52.8
2015-04-01	53.4
2015-07-01	53.6
2015-10-01	53.8
2016-01-01	54.2
2016-04-01	54.8
2016-07-01	54.9
2016-10-01	55.7
2017-01-01	55.4
2017-04-01	55.7
2017-07-01	56.6
2017-10-01	56.8
2018-01-01	56.8
2018-04-01	57.4