Quarter	Percent
1999-01-01	28.4
1999-04-01	30.3
1999-07-01	32.1
1999-10-01	32.2
2000-01-01	33
2000-04-01	34.3
2000-07-01	34.9
2000-10-01	35.7
2001-01-01	34.4
2001-04-01	35.4
2001-07-01	35.9
2001-10-01	36
2002-01-01	35.6
2002-04-01	36.1
2002-07-01	37.1
2002-10-01	38.7
2003-01-01	37.8
2003-04-01	39.4
2003-07-01	39.2
2003-10-01	39.3
2004-01-01	39.3
2004-04-01	39
2004-07-01	39.6
2004-10-01	41
2005-01-01	41.5
2005-04-01	42.1
2005-07-01	42.7
2005-10-01	43
2006-01-01	43.2
2006-04-01	43.2
2006-07-01	42.5
2006-10-01	43
2007-01-01	42.1
2007-04-01	42.3
2007-07-01	42.6
2007-10-01	41.4
2008-01-01	38.8
2008-04-01	39.8
2008-07-01	40
2008-10-01	40.5
2009-01-01	40.6
2009-04-01	41.6
2009-07-01	42.1
2009-10-01	41.5
2010-01-01	41
2010-04-01	42.4
2010-07-01	42.9
2010-10-01	42.4
2011-01-01	42.8
2011-04-01	43.2
2011-07-01	44.2
2011-10-01	44.5
2012-01-01	43.6
2012-04-01	45.7
2012-07-01	46.1
2012-10-01	46.1
2013-01-01	46.8
2013-04-01	49
2013-07-01	49.9
2013-10-01	50.3
2014-01-01	51.1
2014-04-01	52.7
2014-07-01	54.5
2014-10-01	54.4
2015-01-01	55.2
2015-04-01	57.6
2015-07-01	59.0
2015-10-01	59.4
2016-01-01	61.0
2016-04-01	62.0
2016-07-01	62.9
2016-10-01	63.6
2017-01-01	63.1
2017-04-01	64.0
2017-07-01	65.3
2017-10-01	65.6
2018-01-01	65.5
2018-04-01	65.4