Quarter	Percent
1999-01-01	84.8
1999-04-01	84.9
1999-07-01	88.1
1999-10-01	87.5
2000-01-01	87.4
2000-04-01	85.2
2000-07-01	85.7
2000-10-01	85.2
2001-01-01	84.2
2001-04-01	85
2001-07-01	82.9
2001-10-01	82.9
2002-01-01	84.2
2002-04-01	84.6
2002-07-01	85.9
2002-10-01	87.4
2003-01-01	85
2003-04-01	85
2003-07-01	86.5
2003-10-01	83.7
2004-01-01	83.7
2004-04-01	80
2004-07-01	80.2
2004-10-01	83.7
2005-01-01	84
2005-04-01	79.8
2005-07-01	80.4
2005-10-01	80
2006-01-01	79.9
2006-04-01	77.5
2006-07-01	77.5
2006-10-01	79.4
2007-01-01	78.6
2007-04-01	75.7
2007-07-01	75.5
2007-10-01	78.1
2008-01-01	79.5
2008-04-01	77.7
2008-07-01	77.2
2008-10-01	77
2009-01-01	77.2
2009-04-01	74.4
2009-07-01	72.3
2009-10-01	73.8
2010-01-01	75.9
2010-04-01	73.1
2010-07-01	74.9
2010-10-01	74.2
2011-01-01	78.8
2011-04-01	76.4
2011-07-01	74.6
2011-10-01	75.3
2012-01-01	75
2012-04-01	72.7
2012-07-01	73.7
2012-10-01	72.7
2013-01-01	74.3
2013-04-01	71.6
2013-07-01	72.8
2013-10-01	73.4
2014-01-01	71
2014-04-01	67.6
2014-07-01	67.8
2014-10-01	69.2
2015-01-01	69.0
2015-04-01	66.4
2015-07-01	65.7
2015-10-01	67.2
2016-01-01	64.3
2016-04-01	64.0
2016-07-01	67.0
2016-10-01	63.9
2017-01-01	62.3
2017-04-01	59.7
2017-07-01	60.8
2017-10-01	59.1
2018-01-01	58.3
2018-04-01	54.5