Quarter	Percent
1999-01-01	72.9
2000-01-01	71.8
2001-01-01	71.5
2002-01-01	69
2003-01-01	65.3
2003-04-01	64.3
2003-07-01	65.9
2003-10-01	65.2
2004-01-01	64.9
2004-04-01	64.2
2004-07-01	63.6
2004-10-01	63.1
2005-01-01	62.4
2005-04-01	61.7
2005-07-01	63.0
2005-10-01	63.4
2006-01-01	62.3
2006-04-01	62.1
2006-07-01	62.6
2006-10-01	62.6
2007-01-01	62.3
2007-04-01	61.5
2007-07-01	63.2
2007-10-01	62.7
2008-01-01	63.3
2008-04-01	62.6
2008-07-01	62.9
2008-10-01	62.2
2009-01-01	61.7
2009-04-01	60.8
2009-07-01	62.0
2009-10-01	61.5
2010-01-01	61.1
2010-04-01	60.4
2010-07-01	60.3
2010-10-01	60.3
2011-01-01	60.2
2011-04-01	58.6
2011-07-01	58.8
2011-10-01	57.5
2012-01-01	57.0
2012-04-01	55.9
2012-07-01	55.8
2012-10-01	54.3
2013-01-01	54.6
2013-04-01	54.3
2013-07-01	53.6
2013-10-01	53.5
2014-01-01	52.7
2014-04-01	51.3
2014-07-01	51.2
2014-10-01	50.8
2015-01-01	50.4
2015-04-01	49.0
2015-07-01	49.6
2015-10-01	49.9
2016-01-01	49.1
2016-04-01	48.7
2016-07-01	48.4
2016-10-01	48.3
2017-01-01	47.2
2017-04-01	46.6
2017-07-01	47.4
2017-10-01	46.9
2018-01-01	45.9
2018-04-01	46.3