Quarter	Percent
1999-04-01	35.4
2000-04-01	37.9
2001-04-01	35.3
2002-04-01	37.6
2003-01-01	39.7
2003-04-01	39.7
2003-07-01	39.7
2003-10-01	39.7
2004-01-01	38.3
2004-04-01	38.3
2004-07-01	38.3
2004-10-01	38.3
2005-01-01	38.3
2005-04-01	38.3
2005-07-01	38.3
2005-10-01	38.3
2006-01-01	38.7
2006-04-01	38.7
2006-07-01	38.7
2006-10-01	38.7
2007-01-01	32
2007-04-01	39.5
2007-07-01	38.1
2007-10-01	32.5
2008-01-01	31.1
2008-04-01	44.2
2008-07-01	42.8
2008-10-01	36.5
2009-01-01	48.1
2009-04-01	51.4
2009-07-01	44.8
2009-10-01	41.9
2010-01-01	46.8
2010-04-01	50.2
2010-07-01	46.6
2010-10-01	47
2011-01-01	46
2011-04-01	43.4
2011-07-01	50.7
2011-10-01	47.7
2012-01-01	48.9
2012-04-01	44.9
2012-07-01	47.1
2012-10-01	48.8
2013-01-01	51.7
2013-04-01	49.7
2013-07-01	45.7
2013-10-01	45.9
2014-01-01	44.2
2014-04-01	52.9
2014-07-01	50.8
2014-10-01	51.3
2015-01-01	47.1
2015-04-01	46.3
2015-07-01	37.8
2015-10-01	40.9
2016-01-01	46.3
2016-04-01	48.8
2016-07-01	44.6
2016-10-01	45.8
2017-01-01	48.6
2017-04-01	46.0
2017-07-01	43.9
2017-10-01	43.1
2018-01-01	43.6
2018-04-01	43.9