Quarter	Percent
1999-01-01	49.1
2000-01-01	50
2001-01-01	50.7
2002-01-01	50.9
2003-01-01	51.7
2003-04-01	51.8
2003-07-01	52.1
2003-10-01	51.3
2004-01-01	51.2
2004-04-01	51.6
2004-07-01	52.0
2004-10-01	51.3
2005-01-01	51.2
2005-04-01	51.7
2005-07-01	51.8
2005-10-01	51.1
2006-01-01	50.9
2006-04-01	51.4
2006-07-01	51.9
2006-10-01	51.4
2007-01-01	51.3
2007-04-01	51.9
2007-07-01	52.5
2007-10-01	52.1
2008-01-01	52.1
2008-04-01	52.5
2008-07-01	52.7
2008-10-01	52.2
2009-01-01	51.6
2009-04-01	51.9
2009-07-01	51.9
2009-10-01	51.2
2010-01-01	51.2
2010-04-01	51.7
2010-07-01	51.9
2010-10-01	51.2
2011-01-01	51
2011-04-01	51.5
2011-07-01	51.6
2011-10-01	51.1
2012-01-01	50.9
2012-04-01	51.3
2012-07-01	51.5
2012-10-01	51.0
2013-01-01	50.5
2013-04-01	51.0
2013-07-01	51.2
2013-10-01	50.6
2014-01-01	50.2
2014-04-01	50.5
2014-07-01	50.5
2014-10-01	50.1
2015-01-01	49.9
2015-04-01	50.4
2015-07-01	50.6
2015-10-01	50.2
2016-01-01	50.0
2016-04-01	50.5
2016-07-01	50.6
2016-10-01	50.1
2017-01-01	49.9
2017-04-01	50.8
2017-07-01	50.7
2017-10-01	50.7
2018-01-01	50.4
2018-04-01	50.8