Quarter	Percent
1998-01-01	51.3
1998-04-01	51.2
1998-07-01	50.6
1998-10-01	50.7
1999-01-01	49.5
1999-04-01	49.6
1999-07-01	49.8
1999-10-01	49.8
2000-01-01	49.8
2000-04-01	49.4
2000-07-01	49.2
2000-10-01	49.6
2001-01-01	49.7
2001-04-01	50.2
2001-07-01	50.2
2001-10-01	50.7
2002-01-01	49.7
2002-04-01	48.8
2002-07-01	48.3
2002-10-01	48.4
2003-01-01	48.3
2003-04-01	47.8
2003-07-01	47.4
2003-10-01	47.4
2004-01-01	46.2
2004-04-01	45.8
2004-07-01	45.7
2004-10-01	45.7
2005-01-01	46
2005-04-01	45.5
2005-07-01	45.4
2005-10-01	45.3
2006-01-01	45.2
2006-04-01	45.1
2006-07-01	44.7
2006-10-01	45.2
2007-01-01	45.2
2007-04-01	45
2007-07-01	45.1
2007-10-01	45.3
2008-01-01	45.4
2008-04-01	44.9
2008-07-01	44.9
2008-10-01	44.7
2009-01-01	44.1
2009-04-01	43.6
2009-07-01	43.1
2009-10-01	43.3
2010-01-01	42.9
2010-04-01	42.4
2010-07-01	42.3
2010-10-01	42.4
2011-01-01	42.6
2011-04-01	42.8
2011-07-01	42.7
2011-10-01	42.1
2012-01-01	42
2012-04-01	41.9
2012-07-01	41.5
2012-10-01	41.5
2013-01-01	42
2013-04-01	41.4
2013-07-01	41.5
2013-10-01	41.9
2014-01-01	41.3
2014-04-01	41
2014-07-01	40.8
2014-10-01	40.9
2015-01-01	40.7
2015-04-01	40.1
2015-07-01	39.7
2015-10-01	39.8
2016-01-01	39.8
2016-04-01	39.4
2016-07-01	39.1
2016-10-01	39.9
2017-01-01	39.9
2017-04-01	39.1
2017-07-01	39.7
2017-10-01	40.3
2018-01-01	40.6
2018-04-01	39.6