Quarter	Percent
1998-01-01	81.9
1999-01-01	81.7
1999-04-01	82.7
1999-07-01	83.2
1999-10-01	85
2000-01-01	81.1
2000-04-01	82.2
2000-07-01	83.3
2000-10-01	81.3
2001-01-01	81.7
2001-04-01	80.7
2001-07-01	82.1
2001-10-01	80.4
2002-01-01	80.7
2002-04-01	80.3
2002-07-01	79.4
2002-10-01	79.1
2003-01-01	79.8
2003-04-01	77.3
2003-07-01	78.2
2003-10-01	77.8
2004-01-01	81.9
2004-04-01	81.5
2004-07-01	81.6
2004-10-01	79.8
2005-01-01	79.3
2005-04-01	77.6
2005-07-01	76.4
2005-10-01	76.9
2006-01-01	75.7
2006-04-01	75.1
2006-07-01	74.9
2006-10-01	73.7
2007-01-01	73.1
2007-04-01	73
2007-07-01	72.5
2007-10-01	71.6
2008-01-01	70.4
2008-04-01	70.5
2008-07-01	69.1
2008-10-01	69.7
2009-01-01	69.6
2009-04-01	69.4
2009-07-01	69
2009-10-01	67.7
2010-01-01	66.3
2010-04-01	66.2
2010-07-01	65.6
2010-10-01	67.5
2011-01-01	66.9
2011-04-01	66.7
2011-07-01	66.8
2011-10-01	67.6
2012-01-01	66.7
2012-04-01	65.2
2012-07-01	65.3
2012-10-01	64.8
2013-01-01	64.8
2013-04-01	63
2013-07-01	63.3
2013-10-01	63.4
2014-01-01	64.1
2014-04-01	62.2
2014-07-01	62
2014-10-01	61.8
2015-01-01	61.2
2015-04-01	59.6
2015-07-01	59.5
2015-10-01	59.0
2016-01-01	58.7
2016-04-01	56.7
2016-07-01	56.9
2016-10-01	56.8
2017-01-01	56.7
2017-04-01	56.2
2017-07-01	54.9
2017-10-01	54.5
2018-01-01	53.7
2018-04-01	54.3