Quarter	Percent
1999-01-01	25
2000-01-01	26.1
2001-01-01	26.7
2002-01-01	29.6
2003-01-01	33.3
2003-04-01	34.2
2003-07-01	33
2003-10-01	32.9
2004-01-01	32.7
2004-04-01	34
2004-07-01	35.1
2004-10-01	34.9
2005-01-01	35.9
2005-04-01	36.6
2005-07-01	35.5
2005-10-01	34.9
2006-01-01	35.8
2006-04-01	35.9
2006-07-01	35.9
2006-10-01	35.7
2007-01-01	35.7
2007-04-01	37.0
2007-07-01	35.8
2007-10-01	35.7
2008-01-01	35.4
2008-04-01	36.2
2008-07-01	35.9
2008-10-01	36
2009-01-01	36.3
2009-04-01	37.1
2009-07-01	36.5
2009-10-01	36.1
2010-01-01	36.7
2010-04-01	37.5
2010-07-01	37.9
2010-10-01	37.3
2011-01-01	37.4
2011-04-01	39.1
2011-07-01	39.2
2011-10-01	39.9
2012-01-01	40.5
2012-04-01	41.3
2012-07-01	42
2012-10-01	42.7
2013-01-01	42.4
2013-04-01	43.1
2013-07-01	43.4
2013-10-01	43.1
2014-01-01	43.8
2014-04-01	45.6
2014-07-01	45.4
2014-10-01	45.9
2015-01-01	46.1
2015-04-01	47.5
2015-07-01	47.1
2015-10-01	46.8
2016-01-01	47.6
2016-04-01	48.3
2016-07-01	48.3
2016-10-01	48.4
2017-01-01	49.3
2017-04-01	50.5
2017-07-01	49.8
2017-10-01	50.1
2018-01-01	50.6
2018-04-01	50.1