Quarter	Percent
1999-04-01	57.3
1999-07-01	60
1999-10-01	59.7
2000-01-01	58.1
2000-04-01	58
2000-07-01	60.2
2000-10-01	58.5
2001-01-01	57.7
2001-04-01	57.9
2001-07-01	60.7
2001-10-01	59.4
2002-01-01	57.5
2002-04-01	57.1
2002-07-01	58.4
2002-10-01	58.1
2003-01-01	56.7
2003-04-01	55.7
2003-07-01	58.2
2003-10-01	57.9
2004-01-01	56.7
2004-04-01	56.5
2004-07-01	58
2004-10-01	56.9
2005-01-01	56.0
2005-04-01	54.9
2005-07-01	57.0
2005-10-01	55.5
2006-01-01	53.6
2006-04-01	53.4
2006-07-01	56.8
2006-10-01	55.1
2007-01-01	53.5
2007-04-01	52.6
2007-07-01	54.8
2007-10-01	55.0
2008-01-01	53.1
2008-04-01	52.7
2008-07-01	54.6
2008-10-01	53.0
2009-01-01	48.7
2009-04-01	47.6
2009-07-01	48.3
2009-10-01	47
2010-01-01	44.7
2010-04-01	46.9
2010-07-01	50.3
2010-10-01	48.3
2011-01-01	45.6
2011-04-01	46.3
2011-07-01	47.1
2011-10-01	46.2
2012-01-01	44.4
2012-04-01	45.9
2012-07-01	48
2012-10-01	47.1
2013-01-01	45.3
2013-04-01	45
2013-07-01	47.8
2013-10-01	47.4
2014-01-01	46.2
2014-04-01	47.6
2014-07-01	49.6
2014-10-01	49.5
2015-01-01	48.7
2015-04-01	48.4
2015-07-01	51.9
2015-10-01	52.1
2016-01-01	50.7
2016-04-01	49.7
2016-07-01	50.8
2016-10-01	51.0
2017-01-01	49.9
2017-04-01	50.1
2017-07-01	50.6
2017-10-01	51.2
2018-01-01	50.9
2018-04-01	51.0