Quarter	Percent
1998-01-01	31.5
1998-04-01	32.2
1998-07-01	32.7
1998-10-01	32.8
1999-01-01	32.5
1999-04-01	33
1999-07-01	33.6
1999-10-01	33.6
2000-01-01	33.2
2000-04-01	34
2000-07-01	34.7
2000-10-01	35.1
2001-01-01	34.9
2001-04-01	35.4
2001-07-01	35.9
2001-10-01	36
2002-01-01	35.9
2002-04-01	36.2
2002-07-01	36.7
2002-10-01	36.6
2003-01-01	36.4
2003-04-01	37
2003-07-01	37.3
2003-10-01	37
2004-01-01	38.8
2004-04-01	39.2
2004-07-01	39.2
2004-10-01	39.6
2005-01-01	38.9
2005-04-01	39.2
2005-07-01	38.7
2005-10-01	39.4
2006-01-01	39.4
2006-04-01	40.1
2006-07-01	39.7
2006-10-01	40.2
2007-01-01	39.5
2007-04-01	40.2
2007-07-01	40.3
2007-10-01	40.5
2008-01-01	40.4
2008-04-01	41
2008-07-01	40.7
2008-10-01	40.7
2009-01-01	40
2009-04-01	40.5
2009-07-01	39.7
2009-10-01	39.8
2010-01-01	39.5
2010-04-01	40.2
2010-07-01	39.6
2010-10-01	40.2
2011-01-01	40.2
2011-04-01	40.4
2011-07-01	39.8
2011-10-01	40.5
2012-01-01	40.4
2012-04-01	41
2012-07-01	40.4
2012-10-01	40.7
2013-01-01	40.1
2013-04-01	40.2
2013-07-01	39.8
2013-10-01	40.3
2014-01-01	40
2014-04-01	40.3
2014-07-01	40.3
2014-10-01	40.7
2015-01-01	40.3
2015-04-01	40.8
2015-07-01	40.6
2015-10-01	40.9
2016-01-01	40.7
2016-04-01	41.8
2016-07-01	41.5
2016-10-01	41.6
2017-01-01	41.6
2017-04-01	42.3
2017-07-01	42.3
2017-10-01	42.5
2018-01-01	42.1
2018-04-01	43.3