Quarter	Percent
1998-01-01	61.4
1998-04-01	61.1
1998-07-01	61.9
1998-10-01	61.3
1999-01-01	60.8
1999-04-01	60.5
1999-07-01	60.7
1999-10-01	60.4
2000-01-01	60.9
2000-04-01	61.9
2000-07-01	61.8
2000-10-01	62.4
2001-01-01	61.7
2001-04-01	61.4
2001-07-01	60.9
2001-10-01	60.1
2002-01-01	58.6
2002-04-01	58.1
2002-07-01	57
2002-10-01	56.6
2003-01-01	56.2
2003-04-01	55.7
2003-07-01	55.2
2003-10-01	56
2004-01-01	55
2004-04-01	55.1
2004-07-01	54.8
2004-10-01	54.8
2005-01-01	53.7
2005-04-01	53.4
2005-07-01	52.3
2005-10-01	53.1
2006-01-01	51.8
2006-04-01	52.1
2006-07-01	52.2
2006-10-01	52.9
2007-01-01	52.3
2007-04-01	51.9
2007-07-01	51.4
2007-10-01	51.4
2008-01-01	50.9
2008-04-01	50.2
2008-07-01	50.7
2008-10-01	50.1
2009-01-01	49.8
2009-04-01	49.9
2009-07-01	50.4
2009-10-01	51.2
2010-01-01	50.5
2010-04-01	50.4
2010-07-01	50.4
2010-10-01	49.8
2011-01-01	49.3
2011-04-01	48.9
2011-07-01	49.4
2011-10-01	50
2012-01-01	49.5
2012-04-01	48
2012-07-01	46.8
2012-10-01	46.2
2013-01-01	46
2013-04-01	45.5
2013-07-01	44.9
2013-10-01	44.4
2014-01-01	44
2014-04-01	43.9
2014-07-01	42.5
2014-10-01	42.3
2015-01-01	42.6
2015-04-01	41.9
2015-07-01	41.8
2015-10-01	41.8
2016-01-01	40.6
2016-04-01	39.5
2016-07-01	38.9
2016-10-01	37.6
2017-01-01	37.2
2017-04-01	36.8
2017-07-01	36.1
2017-10-01	35.3
2018-01-01	34.2
2018-04-01	33.6