Quarter	Percent
1999-01-01	69.1
2000-01-01	68.3
2001-01-01	67.4
2002-01-01	64.4
2003-01-01	61.8
2003-04-01	61.1
2003-07-01	61.5
2003-10-01	60.8
2004-01-01	60.3
2004-04-01	60.3
2004-07-01	60.3
2004-10-01	60.1
2005-01-01	59.4
2005-04-01	59.0
2005-07-01	60.0
2005-10-01	60.1
2006-01-01	59.7
2006-04-01	59.5
2006-07-01	60.3
2006-10-01	60.2
2007-01-01	59.8
2007-04-01	59.3
2007-07-01	60.5
2007-10-01	60.5
2008-01-01	60.8
2008-04-01	60.1
2008-07-01	60.4
2008-10-01	59.7
2009-01-01	59.3
2009-04-01	58.2
2009-07-01	59.2
2009-10-01	58.6
2010-01-01	58.5
2010-04-01	57.7
2010-07-01	57.6
2010-10-01	57.6
2011-01-01	57.4
2011-04-01	56.2
2011-07-01	56.1
2011-10-01	54.8
2012-01-01	54.1
2012-04-01	52.9
2012-07-01	52.4
2012-10-01	51.0
2013-01-01	51.3
2013-04-01	51
2013-07-01	50.8
2013-10-01	50.7
2014-01-01	50.0
2014-04-01	49.4
2014-07-01	49.4
2014-10-01	48.4
2015-01-01	48.2
2015-04-01	46.9
2015-07-01	47.3
2015-10-01	47.3
2016-01-01	46.8
2016-04-01	46.5
2016-07-01	46.1
2016-10-01	46.0
2017-01-01	45.7
2017-04-01	44.9
2017-07-01	45.5
2017-10-01	44.5
2018-01-01	44.2
2018-04-01	44.1