Quarter	Percent
1998-04-01	76.2
1999-01-01	73.7
1999-04-01	73.8
1999-07-01	74.3
1999-10-01	74.8
2000-01-01	73.3
2000-04-01	74.1
2000-07-01	71.7
2000-10-01	72.4
2001-01-01	74.3
2001-04-01	74
2001-07-01	74.2
2001-10-01	73.8
2002-01-01	72.2
2002-04-01	73.3
2002-07-01	71.7
2002-10-01	72
2003-01-01	72.7
2003-04-01	71.5
2003-07-01	70.7
2003-10-01	69.5
2004-01-01	69.5
2004-04-01	68.7
2004-07-01	68.2
2004-10-01	68.9
2005-01-01	68
2005-04-01	66.5
2005-07-01	65.8
2005-10-01	66.6
2006-01-01	67.3
2006-04-01	67.8
2006-07-01	66.1
2006-10-01	64.4
2007-01-01	63.9
2007-04-01	64.8
2007-07-01	64.3
2007-10-01	63.5
2008-01-01	63.9
2008-04-01	65.9
2008-07-01	62.3
2008-10-01	63.5
2009-01-01	64.1
2009-04-01	63.1
2009-07-01	62.2
2009-10-01	62
2010-01-01	61.5
2010-04-01	61.2
2010-07-01	60.4
2010-10-01	60.4
2011-01-01	61.1
2011-04-01	58.3
2011-07-01	59.5
2011-10-01	59.8
2012-01-01	59.8
2012-04-01	58
2012-07-01	57.8
2012-10-01	59.1
2013-01-01	56.9
2013-04-01	56.2
2013-07-01	54.5
2013-10-01	56
2014-01-01	56.6
2014-04-01	54.1
2014-07-01	55.5
2014-10-01	53.5
2015-01-01	54.3
2015-04-01	53.4
2015-07-01	52.8
2015-10-01	53.0
2016-01-01	53.5
2016-04-01	51.2
2016-07-01	51.7
2016-10-01	50.9
2017-01-01	50.2
2017-04-01	49.1
2017-07-01	48.2
2017-10-01	47.4
2018-01-01	48.0
2018-04-01	48.0