Quarter	Percent
1999-04-01	58.9
1999-07-01	59.3
1999-10-01	58.5
2000-01-01	57.8
2000-04-01	57.4
2000-07-01	56.9
2000-10-01	56.5
2001-01-01	56.3
2001-04-01	56.1
2001-07-01	56.1
2001-10-01	55.6
2002-01-01	55.2
2002-04-01	54.4
2002-07-01	54.3
2002-10-01	53.7
2003-01-01	53.6
2003-04-01	52.8
2003-07-01	52.4
2003-10-01	52.3
2004-01-01	52.4
2004-04-01	51.8
2004-07-01	52.6
2004-10-01	51.8
2005-01-01	51.3
2005-04-01	51
2005-07-01	51.2
2005-10-01	51
2006-01-01	50.4
2006-04-01	49.9
2006-07-01	49.6
2006-10-01	49.5
2007-01-01	49.8
2007-04-01	50.1
2007-07-01	50.4
2007-10-01	49.9
2008-01-01	50
2008-04-01	50
2008-07-01	50.0
2008-10-01	49.2
2009-01-01	49.4
2009-04-01	49.2
2009-07-01	49.5
2009-10-01	49.3
2010-01-01	48.7
2010-04-01	49.4
2010-07-01	48.3
2010-10-01	49.1
2011-01-01	48.8
2011-04-01	49
2011-07-01	48.4
2011-10-01	48.7
2012-01-01	47.6
2012-04-01	47
2012-07-01	47.3
2012-10-01	46.2
2013-01-01	45.5
2013-04-01	44.9
2013-07-01	44.5
2013-10-01	44.0
2014-01-01	43.7
2014-04-01	43.6
2014-07-01	44.0
2014-10-01	43.1
2015-01-01	42.6
2015-04-01	42.9
2015-07-01	42.0
2015-10-01	41.7
2016-01-01	41.1
2016-04-01	40.3
2016-07-01	41.1
2016-10-01	40.5
2017-01-01	39.7
2017-04-01	39.6
2017-07-01	38.9
2017-10-01	38.2
2018-01-01	37.7
2018-04-01	37.7