Quarter	Percent
1998-01-01	48.1
1998-04-01	47.8
1998-07-01	47.3
1998-10-01	47.4
1999-01-01	46.8
1999-04-01	46.7
1999-07-01	46.3
1999-10-01	46.7
2000-01-01	46.1
2000-04-01	46.1
2000-07-01	46.2
2000-10-01	46.3
2001-01-01	46.4
2001-04-01	46.2
2001-07-01	46.1
2001-10-01	46.1
2002-01-01	46
2002-04-01	46.4
2002-07-01	46.4
2002-10-01	46.5
2003-01-01	46
2003-04-01	46
2003-07-01	45.5
2003-10-01	45.6
2004-01-01	45.4
2004-04-01	45.6
2004-07-01	45.5
2004-10-01	45.6
2005-01-01	45.3
2005-04-01	45.5
2005-07-01	45.9
2005-10-01	46.1
2006-01-01	45.9
2006-04-01	46.2
2006-07-01	46.1
2006-10-01	46.2
2007-01-01	46.2
2007-04-01	46.6
2007-07-01	46.4
2007-10-01	46.5
2008-01-01	46.3
2008-04-01	46.8
2008-07-01	46.5
2008-10-01	46.6
2009-01-01	45.8
2009-04-01	45.8
2009-07-01	45.5
2009-10-01	45.6
2010-01-01	44.8
2010-04-01	45.1
2010-07-01	45.2
2010-10-01	45.5
2011-01-01	45.2
2011-04-01	45.5
2011-07-01	45.7
2011-10-01	45.8
2012-01-01	45.4
2012-04-01	45.9
2012-07-01	46.1
2012-10-01	46.3
2013-01-01	46.2
2013-04-01	46.9
2013-07-01	46.7
2013-10-01	47
2014-01-01	46.6
2014-04-01	46.8
2014-07-01	47.1
2014-10-01	47.8
2015-01-01	47.6
2015-04-01	48.2
2015-07-01	48.3
2015-10-01	48.4
2016-01-01	48.8
2016-04-01	49.4
2016-07-01	49.4
2016-10-01	50.1
2017-01-01	49.9
2017-04-01	50.1
2017-07-01	50.8
2017-10-01	50.9
2018-01-01	50.8
2018-04-01	51.2