Quarter	Percent
1999-01-01	71.6
1999-04-01	69.7
1999-07-01	67.9
1999-10-01	67.8
2000-01-01	67
2000-04-01	65.7
2000-07-01	65.1
2000-10-01	64.3
2001-01-01	65.6
2001-04-01	64.6
2001-07-01	64.1
2001-10-01	64
2002-01-01	64.4
2002-04-01	63.9
2002-07-01	62.9
2002-10-01	61.3
2003-01-01	62.2
2003-04-01	60.6
2003-07-01	60.8
2003-10-01	60.7
2004-01-01	60.7
2004-04-01	61
2004-07-01	60.4
2004-10-01	59
2005-01-01	58.5
2005-04-01	57.9
2005-07-01	57.3
2005-10-01	57
2006-01-01	56.8
2006-04-01	56.8
2006-07-01	57.5
2006-10-01	57
2007-01-01	57.9
2007-04-01	57.7
2007-07-01	57.4
2007-10-01	58.6
2008-01-01	61.2
2008-04-01	60.2
2008-07-01	60
2008-10-01	59.5
2009-01-01	59.4
2009-04-01	58.4
2009-07-01	57.9
2009-10-01	58.5
2010-01-01	59
2010-04-01	57.6
2010-07-01	57.1
2010-10-01	57.6
2011-01-01	57.2
2011-04-01	56.8
2011-07-01	55.8
2011-10-01	55.5
2012-01-01	56.4
2012-04-01	54.3
2012-07-01	53.9
2012-10-01	53.9
2013-01-01	53.2
2013-04-01	51
2013-07-01	50.1
2013-10-01	49.7
2014-01-01	48.9
2014-04-01	47.3
2014-07-01	45.5
2014-10-01	45.6
2015-01-01	44.8
2015-04-01	42.4
2015-07-01	41.0
2015-10-01	40.6
2016-01-01	39.0
2016-04-01	38.0
2016-07-01	37.1
2016-10-01	36.4
2017-01-01	36.9
2017-04-01	36.0
2017-07-01	34.7
2017-10-01	34.4
2018-01-01	34.5
2018-04-01	34.6