Quarter	Percent
1999-01-01	38.6
1999-04-01	36.4
1999-07-01	35.8
1999-10-01	36.6
2000-01-01	35.1
2000-04-01	35.2
2000-07-01	35.3
2000-10-01	36.2
2001-01-01	36.5
2001-04-01	37.7
2001-07-01	37.7
2001-10-01	39.1
2002-01-01	38.7
2002-04-01	38.1
2002-07-01	39
2002-10-01	40.5
2003-01-01	38.7
2003-04-01	41.1
2003-07-01	42.6
2003-10-01	41.8
2004-01-01	42.1
2004-04-01	42.8
2004-07-01	44.9
2004-10-01	45.4
2005-01-01	45.8
2005-04-01	47
2005-07-01	49
2005-10-01	49.2
2006-01-01	49.3
2006-04-01	48.7
2006-07-01	50.6
2006-10-01	50.4
2007-01-01	50.8
2007-04-01	51.6
2007-07-01	54
2007-10-01	53.6
2008-01-01	54.6
2008-04-01	55.6
2008-07-01	58.4
2008-10-01	58
2009-01-01	55.7
2009-04-01	54.9
2009-07-01	55.3
2009-10-01	53.8
2010-01-01	54.4
2010-04-01	54.9
2010-07-01	54.2
2010-10-01	52.6
2011-01-01	51.9
2011-04-01	52.5
2011-07-01	53.2
2011-10-01	52.2
2012-01-01	52.3
2012-04-01	54.2
2012-07-01	53.4
2012-10-01	54.8
2013-01-01	53.9
2013-04-01	53.6
2013-07-01	53.7
2013-10-01	51.9
2014-01-01	51.2
2014-04-01	53.1
2014-07-01	54.5
2014-10-01	53.8
2015-01-01	53.2
2015-04-01	53.2
2015-07-01	53.8
2015-10-01	54.1
2016-01-01	54.3
2016-04-01	55.5
2016-07-01	55.0
2016-10-01	55.5
2017-01-01	55.5
2017-04-01	56.1
2017-07-01	57.3
2017-10-01	57.6
2018-01-01	58.4
2018-04-01	57.5