Quarter	Percent
1999-04-01	42.8
1999-07-01	52.4
1999-10-01	45.6
2000-01-01	43.9
2000-04-01	43.5
2000-07-01	53.2
2000-10-01	45.6
2001-01-01	44.2
2001-04-01	42.2
2001-07-01	51.1
2001-10-01	44.4
2002-01-01	43.4
2002-04-01	41.6
2002-07-01	49.4
2002-10-01	43.5
2003-01-01	42.4
2003-04-01	42.3
2003-07-01	48.7
2003-10-01	44.2
2004-01-01	43.1
2004-04-01	41.4
2004-07-01	48.4
2004-10-01	45.8
2005-01-01	44.2
2005-04-01	44.1
2005-07-01	49.8
2005-10-01	45.5
2006-01-01	44.3
2006-04-01	44.4
2006-07-01	50.6
2006-10-01	46.5
2007-01-01	57.0
2007-04-01	58.2
2007-07-01	62.9
2007-10-01	58.4
2008-01-01	56.3
2008-04-01	56.7
2008-07-01	57.6
2008-10-01	52.0
2009-01-01	49.7
2009-04-01	48.4
2009-07-01	47.7
2009-10-01	45.1
2010-01-01	40.4
2010-04-01	41.2
2010-07-01	41.8
2010-10-01	40.1
2011-01-01	38.5
2011-04-01	38.5
2011-07-01	38.4
2011-10-01	37.3
2012-01-01	36.6
2012-04-01	36.9
2012-07-01	38.4
2012-10-01	36.9
2013-01-01	35.2
2013-04-01	37.3
2013-07-01	40.1
2013-10-01	36.2
2014-01-01	33.8
2014-04-01	33.9
2014-07-01	40.6
2014-10-01	38.8
2015-01-01	34.9
2015-04-01	35.8
2015-07-01	40.3
2015-10-01	38.1
2016-01-01	36.9
2016-04-01	42.8
2016-07-01	44.9
2016-10-01	42.7
2017-01-01	40.1
2017-04-01	41.6
2017-07-01	38.3
2017-10-01	39.0
2018-01-01	36.0
2018-04-01	39.2