Quarter	Percent
1999-01-01	81.8
1999-04-01	80.4
1999-07-01	79.2
1999-10-01	78.9
2000-01-01	78.5
2000-04-01	77.4
2000-07-01	76.6
2000-10-01	76
2001-01-01	76.7
2001-04-01	76.2
2001-07-01	75.2
2001-10-01	75.1
2002-01-01	74.9
2002-04-01	74.3
2002-07-01	73.4
2002-10-01	71.8
2003-01-01	71.6
2003-04-01	70.3
2003-07-01	69.9
2003-10-01	69.1
2004-01-01	68.7
2004-04-01	68.7
2004-07-01	67.9
2004-10-01	66.6
2005-01-01	66.5
2005-04-01	65.8
2005-07-01	65.3
2005-10-01	65.1
2006-01-01	65.4
2006-04-01	65.2
2006-07-01	65.8
2006-10-01	65.5
2007-01-01	66.2
2007-04-01	65.8
2007-07-01	66.3
2007-10-01	66.9
2008-01-01	68.1
2008-04-01	67.8
2008-07-01	67.1
2008-10-01	66.7
2009-01-01	66.7
2009-04-01	66
2009-07-01	65.8
2009-10-01	65.1
2010-01-01	65.1
2010-04-01	63.8
2010-07-01	62.8
2010-10-01	62.5
2011-01-01	62
2011-04-01	61.3
2011-07-01	60.7
2011-10-01	60.7
2012-01-01	61.4
2012-04-01	60.1
2012-07-01	60
2012-10-01	60.6
2013-01-01	60.5
2013-04-01	58.9
2013-07-01	58.1
2013-10-01	57.5
2014-01-01	57
2014-04-01	55.7
2014-07-01	54.5
2014-10-01	54.5
2015-01-01	53.8
2015-04-01	52.1
2015-07-01	50.9
2015-10-01	50.8
2016-01-01	49.3
2016-04-01	48.0
2016-07-01	47.3
2016-10-01	46.8
2017-01-01	47.7
2017-04-01	46.7
2017-07-01	45.7
2017-10-01	45.6
2018-01-01	45.0
2018-04-01	45.2