Quarter	Percent
1998-01-01	52.3
1998-04-01	50.8
1998-07-01	50.5
1998-10-01	51.6
1999-01-01	50.3
1999-04-01	50.5
1999-07-01	51.0
1999-10-01	53
2000-01-01	52
2000-04-01	49.6
2000-07-01	52.1
2000-10-01	52.3
2001-01-01	51.8
2001-04-01	51.5
2001-07-01	53.6
2001-10-01	52.9
2002-01-01	52.7
2002-04-01	52.4
2002-07-01	53.7
2002-10-01	52.8
2003-01-01	50.4
2003-04-01	48.3
2003-07-01	49.1
2003-10-01	48
2004-01-01	47.2
2004-04-01	47.1
2004-07-01	48.2
2004-10-01	46.7
2005-01-01	45.9
2005-04-01	46.3
2005-07-01	46.2
2005-10-01	45.7
2006-01-01	45.4
2006-04-01	45.9
2006-07-01	45.8
2006-10-01	45
2007-01-01	45
2007-04-01	43.7
2007-07-01	45.6
2007-10-01	44.4
2008-01-01	44.7
2008-04-01	43.7
2008-07-01	43
2008-10-01	43
2009-01-01	41
2009-04-01	40.1
2009-07-01	39.8
2009-10-01	39.5
2010-01-01	38.5
2010-04-01	37.5
2010-07-01	38.1
2010-10-01	37.8
2011-01-01	39.9
2011-04-01	38.7
2011-07-01	42.2
2011-10-01	40.8
2012-01-01	38.9
2012-04-01	38.5
2012-07-01	41.5
2012-10-01	38
2013-01-01	36.5
2013-04-01	35.2
2013-07-01	38
2013-10-01	35.2
2014-01-01	34.8
2014-04-01	33.3
2014-07-01	36.9
2014-10-01	34
2015-01-01	33.5
2015-04-01	32.5
2015-07-01	35.2
2015-10-01	35.7
2016-01-01	33.9
2016-04-01	34.3
2016-07-01	36.1
2016-10-01	35.8
2017-01-01	35.2
2017-04-01	34.2
2017-07-01	36.5
2017-10-01	36.3
2018-01-01	35.7
2018-04-01	34.9