Quarter	Percent
1999-04-01	54.3
1999-07-01	54.3
1999-10-01	53.9
2000-01-01	53.7
2000-04-01	53.7
2000-07-01	53.5
2000-10-01	53
2001-01-01	52.4
2001-04-01	52.1
2001-07-01	51.8
2001-10-01	51.5
2002-01-01	51.3
2002-04-01	50.8
2002-07-01	50.6
2002-10-01	50.2
2003-01-01	50.2
2003-04-01	49.6
2003-07-01	49.7
2003-10-01	49.6
2004-01-01	48.9
2004-04-01	49.3
2004-07-01	49.9
2004-10-01	48.7
2005-01-01	47.7
2005-04-01	46.8
2005-07-01	46.8
2005-10-01	46.4
2006-01-01	45.7
2006-04-01	45.3
2006-07-01	45.6
2006-10-01	45.7
2007-01-01	45
2007-04-01	44.6
2007-07-01	44.7
2007-10-01	44.7
2008-01-01	44.6
2008-04-01	44.3
2008-07-01	43.9
2008-10-01	44.3
2009-01-01	44.6
2009-04-01	44.9
2009-07-01	45.0
2009-10-01	46.2
2010-01-01	45.5
2010-04-01	44.5
2010-07-01	44.3
2010-10-01	45.3
2011-01-01	45.0
2011-04-01	44.1
2011-07-01	44.5
2011-10-01	44.5
2012-01-01	45.2
2012-04-01	44.8
2012-07-01	45.0
2012-10-01	44.4
2013-01-01	43.2
2013-04-01	42.9
2013-07-01	42.5
2013-10-01	41.2
2014-01-01	41.7
2014-04-01	41.8
2014-07-01	41.2
2014-10-01	41.1
2015-01-01	40.5
2015-04-01	39.7
2015-07-01	39.8
2015-10-01	38.9
2016-01-01	38.6
2016-04-01	38.8
2016-07-01	39.5
2016-10-01	38.7
2017-01-01	38.1
2017-04-01	37.7
2017-07-01	37.8
2017-10-01	37.6
2018-01-01	37.4
2018-04-01	36.6