Quarter	Percent
1998-01-01	57.5
1999-01-01	56.1
1999-04-01	56.7
1999-07-01	58.3
1999-10-01	60.2
2000-01-01	55.5
2000-04-01	55.7
2000-07-01	57.3
2000-10-01	57.1
2001-01-01	59.8
2001-04-01	56.9
2001-07-01	57.7
2001-10-01	57.1
2002-01-01	59.2
2002-04-01	57.4
2002-07-01	57.7
2002-10-01	57.1
2003-01-01	57.5
2003-04-01	56.7
2003-07-01	57.2
2003-10-01	56.9
2004-01-01	63
2004-04-01	60.6
2004-07-01	61.2
2004-10-01	61.3
2005-01-01	60.9
2005-04-01	59.8
2005-07-01	59.7
2005-10-01	58.1
2006-01-01	56.7
2006-04-01	55.6
2006-07-01	55.8
2006-10-01	55.6
2007-01-01	54.8
2007-04-01	51.1
2007-07-01	51.3
2007-10-01	52.4
2008-01-01	49.7
2008-04-01	49.1
2008-07-01	51.1
2008-10-01	50.6
2009-01-01	51.1
2009-04-01	49.2
2009-07-01	48.5
2009-10-01	49
2010-01-01	49.4
2010-04-01	48.4
2010-07-01	47.8
2010-10-01	48.9
2011-01-01	50.3
2011-04-01	49.2
2011-07-01	49.3
2011-10-01	49.8
2012-01-01	50.6
2012-04-01	47.6
2012-07-01	46.4
2012-10-01	46.4
2013-01-01	47
2013-04-01	44.5
2013-07-01	44.4
2013-10-01	43.8
2014-01-01	44.9
2014-04-01	42.5
2014-07-01	43.2
2014-10-01	42.2
2015-01-01	43.5
2015-04-01	43.5
2015-07-01	42.3
2015-10-01	41.2
2016-01-01	40.0
2016-04-01	38.5
2016-07-01	38.4
2016-10-01	38.5
2017-01-01	38.4
2017-04-01	37.0
2017-07-01	37.0
2017-10-01	35.5
2018-01-01	35.1
2018-04-01	34.1