Quarter	Percent
1999-01-01	89.7
1999-04-01	88.7
1999-07-01	88.1
1999-10-01	87.9
2000-01-01	87.9
2000-04-01	86.8
2000-07-01	86
2000-10-01	85.3
2001-01-01	85.7
2001-04-01	85.6
2001-07-01	84.3
2001-10-01	84.1
2002-01-01	83.4
2002-04-01	82.7
2002-07-01	81.9
2002-10-01	80.2
2003-01-01	79.2
2003-04-01	78.2
2003-07-01	77.2
2003-10-01	76
2004-01-01	75.2
2004-04-01	74.9
2004-07-01	73.9
2004-10-01	72.9
2005-01-01	73.2
2005-04-01	72.3
2005-07-01	72
2005-10-01	71.8
2006-01-01	72.3
2006-04-01	72.1
2006-07-01	72.4
2006-10-01	72.5
2007-01-01	73
2007-04-01	72.3
2007-07-01	73.5
2007-10-01	73.7
2008-01-01	73.8
2008-04-01	74
2008-07-01	73
2008-10-01	72.7
2009-01-01	72.7
2009-04-01	72.3
2009-07-01	72.2
2009-10-01	70.5
2010-01-01	70.1
2010-04-01	69
2010-07-01	67.6
2010-10-01	66.6
2011-01-01	65.9
2011-04-01	65.2
2011-07-01	64.9
2011-10-01	65
2012-01-01	65.6
2012-04-01	65
2012-07-01	65.1
2012-10-01	66.3
2013-01-01	66.6
2013-04-01	65.5
2013-07-01	64.9
2013-10-01	64.1
2014-01-01	63.9
2014-04-01	62.7
2014-07-01	62
2014-10-01	61.9
2015-01-01	61.4
2015-04-01	60.3
2015-07-01	59.3
2015-10-01	59.4
2016-01-01	58.0
2016-04-01	56.5
2016-07-01	55.9
2016-10-01	55.7
2017-01-01	56.8
2017-04-01	55.9
2017-07-01	55.1
2017-10-01	55.0
2018-01-01	54.0
2018-04-01	54.3