Quarter	Percent
1998-04-01	85.8
1999-01-01	82.1
1999-04-01	83.9
1999-07-01	83.1
1999-10-01	83.7
2000-01-01	83.9
2000-04-01	84.2
2000-07-01	81.6
2000-10-01	81.8
2001-01-01	83.8
2001-04-01	84.2
2001-07-01	84.2
2001-10-01	84.3
2002-01-01	81.9
2002-04-01	82.6
2002-07-01	81.7
2002-10-01	80.9
2003-01-01	80.5
2003-04-01	82
2003-07-01	80.5
2003-10-01	80.1
2004-01-01	78.5
2004-04-01	78.2
2004-07-01	77.3
2004-10-01	77.5
2005-01-01	78.2
2005-04-01	76
2005-07-01	76.7
2005-10-01	75.6
2006-01-01	76.6
2006-04-01	75.7
2006-07-01	74.5
2006-10-01	74.7
2007-01-01	73.8
2007-04-01	71.7
2007-07-01	73.1
2007-10-01	71.6
2008-01-01	72.1
2008-04-01	74.5
2008-07-01	69.6
2008-10-01	72.4
2009-01-01	72.7
2009-04-01	70
2009-07-01	69.9
2009-10-01	70.3
2010-01-01	68.6
2010-04-01	70.3
2010-07-01	68.2
2010-10-01	69.4
2011-01-01	68.5
2011-04-01	65
2011-07-01	66.7
2011-10-01	67.9
2012-01-01	67
2012-04-01	63.8
2012-07-01	63.8
2012-10-01	65.7
2013-01-01	63.3
2013-04-01	63.6
2013-07-01	60
2013-10-01	61.7
2014-01-01	63.6
2014-04-01	60.2
2014-07-01	60.3
2014-10-01	60
2015-01-01	60.0
2015-04-01	58.6
2015-07-01	58.8
2015-10-01	57.8
2016-01-01	58.5
2016-04-01	57.4
2016-07-01	57.5
2016-10-01	55.6
2017-01-01	55.8
2017-04-01	53.9
2017-07-01	52.8
2017-10-01	54.5
2018-01-01	54.4
2018-04-01	53.3