Quarter	Percent
1999-04-01	49.6
1999-07-01	58.7
1999-10-01	51.7
2000-01-01	51.2
2000-04-01	52.5
2000-07-01	60.3
2000-10-01	52.7
2001-01-01	52
2001-04-01	51.2
2001-07-01	58.6
2001-10-01	50.5
2002-01-01	49.1
2002-04-01	48.1
2002-07-01	55.3
2002-10-01	49.7
2003-01-01	48.8
2003-04-01	48.4
2003-07-01	54.9
2003-10-01	49.9
2004-01-01	49.3
2004-04-01	48.2
2004-07-01	55.6
2004-10-01	49.7
2005-01-01	49.4
2005-04-01	48.5
2005-07-01	56.7
2005-10-01	51.2
2006-01-01	51.2
2006-04-01	52.2
2006-07-01	58.5
2006-10-01	53.9
2007-01-01	66.5
2007-04-01	66.2
2007-07-01	69.7
2007-10-01	64.9
2008-01-01	60.9
2008-04-01	60.2
2008-07-01	61.2
2008-10-01	51.6
2009-01-01	45.8
2009-04-01	43.7
2009-07-01	42.9
2009-10-01	39.2
2010-01-01	36.4
2010-04-01	37.2
2010-07-01	38.3
2010-10-01	34.3
2011-01-01	33.2
2011-04-01	33.7
2011-07-01	35.5
2011-10-01	34.5
2012-01-01	30.1
2012-04-01	31.9
2012-07-01	34.9
2012-10-01	33.0
2013-01-01	32.7
2013-04-01	35.1
2013-07-01	38.8
2013-10-01	37.2
2014-01-01	34.2
2014-04-01	36.0
2014-07-01	39.5
2014-10-01	37.6
2015-01-01	36.4
2015-04-01	38.3
2015-07-01	41.3
2015-10-01	37.5
2016-01-01	37.7
2016-04-01	43.2
2016-07-01	46.9
2016-10-01	41.5
2017-01-01	39.0
2017-04-01	40.5
2017-07-01	40.5
2017-10-01	40.8
2018-01-01	38.9
2018-04-01	40.8