Quarter	Percent
1998-01-01	48.5
1998-04-01	47.1
1998-07-01	47.1
1998-10-01	48.2
1999-01-01	46.9
1999-04-01	46.3
1999-07-01	47.0
1999-10-01	47.7
2000-01-01	46.8
2000-04-01	44.8
2000-07-01	46.7
2000-10-01	47
2001-01-01	46.8
2001-04-01	46.5
2001-07-01	48.2
2001-10-01	47.8
2002-01-01	47.3
2002-04-01	47.1
2002-07-01	47.9
2002-10-01	48.5
2003-01-01	46.7
2003-04-01	44.9
2003-07-01	45
2003-10-01	44.2
2004-01-01	43.3
2004-04-01	42.6
2004-07-01	44
2004-10-01	42.8
2005-01-01	42.1
2005-04-01	41.8
2005-07-01	42.7
2005-10-01	41.8
2006-01-01	41.4
2006-04-01	41.4
2006-07-01	42.3
2006-10-01	41.5
2007-01-01	41.5
2007-04-01	40.4
2007-07-01	41.9
2007-10-01	41.5
2008-01-01	41.1
2008-04-01	40.5
2008-07-01	41.2
2008-10-01	40.7
2009-01-01	39.8
2009-04-01	38.5
2009-07-01	38.6
2009-10-01	38
2010-01-01	37.1
2010-04-01	35.9
2010-07-01	35.9
2010-10-01	35.6
2011-01-01	38
2011-04-01	36.6
2011-07-01	39.8
2011-10-01	38.3
2012-01-01	36.7
2012-04-01	36.4
2012-07-01	39.1
2012-10-01	36.1
2013-01-01	34.8
2013-04-01	33.9
2013-07-01	36.7
2013-10-01	34.7
2014-01-01	34.2
2014-04-01	32.9
2014-07-01	36.4
2014-10-01	33.6
2015-01-01	33.4
2015-04-01	31.8
2015-07-01	34.9
2015-10-01	33.9
2016-01-01	33.2
2016-04-01	32.3
2016-07-01	33.7
2016-10-01	33.5
2017-01-01	33.4
2017-04-01	32.6
2017-07-01	35.2
2017-10-01	34.8
2018-01-01	33.3
2018-04-01	32.7