Quarter	Percent
1998-01-01	51.9
1998-04-01	51.7
1998-07-01	51.9
1998-10-01	52.2
1999-01-01	52
1999-04-01	52
1999-07-01	52.1
1999-10-01	52.2
2000-01-01	51.9
2000-04-01	51.6
2000-07-01	51.5
2000-10-01	51.5
2001-01-01	51.6
2001-04-01	51.1
2001-07-01	51.2
2001-10-01	51
2002-01-01	50.7
2002-04-01	50.8
2002-07-01	51
2002-10-01	51.3
2003-01-01	50.9
2003-04-01	50.9
2003-07-01	50.7
2003-10-01	50.7
2004-01-01	50.6
2004-04-01	50.5
2004-07-01	50.5
2004-10-01	50.6
2005-01-01	50.2
2005-04-01	50.5
2005-07-01	50.9
2005-10-01	51.1
2006-01-01	50.8
2006-04-01	50.6
2006-07-01	50.5
2006-10-01	50.3
2007-01-01	50
2007-04-01	49.8
2007-07-01	49.6
2007-10-01	49.7
2008-01-01	49.3
2008-04-01	49.4
2008-07-01	49.3
2008-10-01	49.4
2009-01-01	49.2
2009-04-01	49.5
2009-07-01	49.7
2009-10-01	49.7
2010-01-01	49.2
2010-04-01	49.1
2010-07-01	49.4
2010-10-01	49.5
2011-01-01	49.3
2011-04-01	49.4
2011-07-01	49.6
2011-10-01	49.6
2012-01-01	49.4
2012-04-01	49.8
2012-07-01	50.3
2012-10-01	50.6
2013-01-01	50.5
2013-04-01	51
2013-07-01	51
2013-10-01	51.1
2014-01-01	50.7
2014-04-01	50.6
2014-07-01	50.9
2014-10-01	51.3
2015-01-01	51.2
2015-04-01	51.2
2015-07-01	51.4
2015-10-01	51.2
2016-01-01	51.4
2016-04-01	51.7
2016-07-01	52.0
2016-10-01	52.4
2017-01-01	52.1
2017-04-01	52.0
2017-07-01	52.6
2017-10-01	52.4
2018-01-01	52.4
2018-04-01	52.6