Quarter	Percent
1999-01-01	61.1
1999-04-01	60.9
1999-07-01	60.4
1999-10-01	59.8
2000-01-01	59.5
2000-04-01	59.3
2000-07-01	59
2000-10-01	58.8
2001-01-01	60.4
2001-04-01	60.4
2001-07-01	60
2001-10-01	59.6
2002-01-01	58.5
2002-04-01	57.9
2002-07-01	57.5
2002-10-01	57.3
2003-01-01	56.8
2003-04-01	56.4
2003-07-01	55.9
2003-10-01	55.5
2004-01-01	55.3
2004-04-01	55
2004-07-01	54.7
2004-10-01	54.2
2005-01-01	54
2005-04-01	53.4
2005-07-01	53.6
2005-10-01	53.1
2006-01-01	52.6
2006-04-01	52.1
2006-07-01	52.2
2006-10-01	51.5
2007-01-01	51.4
2007-04-01	51.2
2007-07-01	50.9
2007-10-01	50.6
2008-01-01	50.3
2008-04-01	49.8
2008-07-01	49.6
2008-10-01	48.8
2009-01-01	48.6
2009-04-01	48.6
2009-07-01	48.6
2009-10-01	48.4
2010-01-01	48.1
2010-04-01	47.9
2010-07-01	47.8
2010-10-01	47.6
2011-01-01	47.5
2011-04-01	47
2011-07-01	47.2
2011-10-01	47.1
2012-01-01	46.6
2012-04-01	46.6
2012-07-01	46.5
2012-10-01	46.5
2013-01-01	46.5
2013-04-01	46.6
2013-07-01	46.8
2013-10-01	46.6
2014-01-01	46.8
2014-04-01	46.9
2014-07-01	47.2
2014-10-01	46.7
2015-01-01	47.0
2015-04-01	46.6
2015-07-01	47.2
2015-10-01	46.8
2016-01-01	46.9
2016-04-01	46.7
2016-07-01	47.0
2016-10-01	47.2
2017-01-01	47.4
2017-04-01	47.3
2017-07-01	47.5
2017-10-01	47.3
2018-01-01	47.7
2018-04-01	47.4
2018-07-01	47.7