Quarter	Percent
1998-01-01	37.2
1998-04-01	37.5
1998-07-01	36.7
1998-10-01	37.2
1999-01-01	37.4
1999-04-01	37.6
1999-07-01	37.5
1999-10-01	37.7
2000-01-01	36.8
2000-04-01	36.1
2000-07-01	36.3
2000-10-01	35.9
2001-01-01	36.3
2001-04-01	36.9
2001-07-01	37.2
2001-10-01	37.9
2002-01-01	39.5
2002-04-01	40.3
2002-07-01	41.5
2002-10-01	41.7
2003-01-01	42
2003-04-01	42.3
2003-07-01	42.8
2003-10-01	41.9
2004-01-01	42.5
2004-04-01	42.5
2004-07-01	42.9
2004-10-01	42.8
2005-01-01	44
2005-04-01	44.2
2005-07-01	45.2
2005-10-01	44.5
2006-01-01	45.4
2006-04-01	45.4
2006-07-01	45.3
2006-10-01	44.7
2007-01-01	45.3
2007-04-01	45.8
2007-07-01	46.4
2007-10-01	46.5
2008-01-01	47.1
2008-04-01	47.8
2008-07-01	47.5
2008-10-01	48
2009-01-01	47.8
2009-04-01	47.4
2009-07-01	46.4
2009-10-01	45.8
2010-01-01	46
2010-04-01	46.3
2010-07-01	46.5
2010-10-01	47.2
2011-01-01	47.3
2011-04-01	48.2
2011-07-01	47.8
2011-10-01	47.4
2012-01-01	47.5
2012-04-01	49.1
2012-07-01	50.4
2012-10-01	50.3
2013-01-01	50.3
2013-04-01	51.4
2013-07-01	52.2
2013-10-01	52.6
2014-01-01	52.7
2014-04-01	53.6
2014-07-01	54.7
2014-10-01	55
2015-01-01	54.5
2015-04-01	55.6
2015-07-01	55.9
2015-10-01	55.8
2016-01-01	56.5
2016-04-01	58.2
2016-07-01	59.0
2016-10-01	60.4
2017-01-01	60.9
2017-04-01	61.6
2017-07-01	62.6
2017-10-01	63.4
2018-01-01	64.4
2018-04-01	65.1