Quarter	Percent
1999-04-01	73.1
1999-07-01	72.8
1999-10-01	72.6
2000-01-01	72.6
2000-04-01	72.3
2000-07-01	72.2
2000-10-01	71.6
2001-01-01	70.8
2001-04-01	70.8
2001-07-01	70.4
2001-10-01	70.3
2002-01-01	69.5
2002-04-01	68.6
2002-07-01	68.2
2002-10-01	67.5
2003-01-01	67.1
2003-04-01	65.9
2003-07-01	65.7
2003-10-01	66
2004-01-01	65.8
2004-04-01	65.4
2004-07-01	66.4
2004-10-01	64.6
2005-01-01	63.2
2005-04-01	61.6
2005-07-01	61.8
2005-10-01	60.6
2006-01-01	60.2
2006-04-01	59.2
2006-07-01	60.1
2006-10-01	60.5
2007-01-01	59.4
2007-04-01	58.8
2007-07-01	59.4
2007-10-01	58.3
2008-01-01	58.3
2008-04-01	57.2
2008-07-01	56.4
2008-10-01	57.3
2009-01-01	56.2
2009-04-01	56.3
2009-07-01	55.5
2009-10-01	56.3
2010-01-01	55.1
2010-04-01	53.3
2010-07-01	53.2
2010-10-01	54.9
2011-01-01	53.8
2011-04-01	52.7
2011-07-01	52.8
2011-10-01	52.9
2012-01-01	53.4
2012-04-01	53.1
2012-07-01	53.3
2012-10-01	52.9
2013-01-01	52.0
2013-04-01	51.6
2013-07-01	52.0
2013-10-01	51.0
2014-01-01	51.2
2014-04-01	50.7
2014-07-01	50.8
2014-10-01	50.4
2015-01-01	50.6
2015-04-01	49.9
2015-07-01	49.9
2015-10-01	49.3
2016-01-01	47.7
2016-04-01	48.2
2016-07-01	48.8
2016-10-01	47.6
2017-01-01	46.5
2017-04-01	46.0
2017-07-01	47.5
2017-10-01	45.4
2018-01-01	46.5
2018-04-01	45.8