Quarter	Percent
1999-01-01	74.1
2000-01-01	77
2000-04-01	75.6
2000-07-01	74.9
2000-10-01	77.9
2001-01-01	79.9
2001-04-01	76.3
2001-07-01	76.3
2001-10-01	78.8
2002-01-01	79.1
2002-04-01	78.8
2002-07-01	79.8
2002-10-01	78.8
2003-01-01	78.3
2003-04-01	77.6
2003-07-01	78.1
2003-10-01	78.2
2004-01-01	79.3
2004-04-01	79.1
2004-07-01	77.7
2004-10-01	78.4
2005-01-01	80.2
2005-04-01	79
2005-07-01	76.7
2005-10-01	78.2
2006-01-01	81.1
2006-04-01	80.4
2006-07-01	78.1
2006-10-01	79.4
2007-01-01	80.2
2007-04-01	80.5
2007-07-01	78.7
2007-10-01	78.3
2008-01-01	79.1
2008-04-01	78.4
2008-07-01	78
2008-10-01	78
2009-01-01	77.7
2009-04-01	77.3
2009-07-01	76.6
2009-10-01	75.9
2010-01-01	75.9
2010-04-01	74.5
2010-07-01	73.3
2010-10-01	72.8
2011-01-01	72.3
2011-04-01	71.3
2011-07-01	70.4
2011-10-01	69.9
2012-01-01	70.6
2012-04-01	69.4
2012-07-01	67.6
2012-10-01	67.3
2013-01-01	68
2013-04-01	67.1
2013-07-01	66.3
2013-10-01	65.3
2014-01-01	65.3
2014-04-01	65.7
2014-07-01	64.6
2014-10-01	63.8
2015-01-01	63.9
2015-04-01	64.1
2015-07-01	61.6
2015-10-01	61.1
2016-01-01	62.4
2016-04-01	61.8
2016-07-01	60.1
2016-10-01	59.7
2017-01-01	60.6
2017-04-01	58.7
2017-07-01	58.1
2017-10-01	60.4
2018-01-01	60.6
2018-04-01	59.2