Quarter	Percent
1999-04-01	33.2
1999-07-01	28.7
1999-10-01	30.8
2000-01-01	33.1
2000-04-01	33
2000-07-01	29.6
2000-10-01	32.4
2001-01-01	33.3
2001-04-01	34.3
2001-07-01	29.1
2001-10-01	31.5
2002-01-01	33.7
2002-04-01	34.5
2002-07-01	31.5
2002-10-01	32.7
2003-01-01	34.1
2003-04-01	36
2003-07-01	31.6
2003-10-01	33.2
2004-01-01	35.0
2004-04-01	36.0
2004-07-01	32
2004-10-01	34
2005-01-01	35.2
2005-04-01	36.8
2005-07-01	32.9
2005-10-01	34.4
2006-01-01	36.8
2006-04-01	36.9
2006-07-01	31.7
2006-10-01	35.1
2007-01-01	36.6
2007-04-01	37.6
2007-07-01	33.9
2007-10-01	35.3
2008-01-01	37.2
2008-04-01	37.4
2008-07-01	32.9
2008-10-01	35.2
2009-01-01	38.9
2009-04-01	39.3
2009-07-01	36.6
2009-10-01	39.9
2010-01-01	41.8
2010-04-01	40.4
2010-07-01	35.9
2010-10-01	38.2
2011-01-01	41.6
2011-04-01	40.5
2011-07-01	36.5
2011-10-01	38.5
2012-01-01	40.6
2012-04-01	39.7
2012-07-01	37
2012-10-01	38.9
2013-01-01	41.6
2013-04-01	41.2
2013-07-01	37.0
2013-10-01	39.3
2014-01-01	41.6
2014-04-01	41.7
2014-07-01	38.7
2014-10-01	40.0
2015-01-01	41.2
2015-04-01	41.8
2015-07-01	37.9
2015-10-01	39.2
2016-01-01	41.0
2016-04-01	41.8
2016-07-01	39.5
2016-10-01	40.5
2017-01-01	42.2
2017-04-01	42.3
2017-07-01	40.9
2017-10-01	41.2
2018-01-01	41.9
2018-04-01	42.4