Quarter	Percent
1999-01-01	88.4
1999-04-01	88.7
1999-07-01	89.3
1999-10-01	89.4
2000-01-01	88.6
2000-04-01	88.9
2000-07-01	89.9
2000-10-01	89.7
2001-01-01	89.1
2001-04-01	88.9
2001-07-01	88.6
2001-10-01	89.4
2002-01-01	89
2002-04-01	89.4
2002-07-01	88.8
2002-10-01	88.4
2003-01-01	88.6
2003-04-01	87.8
2003-07-01	87.1
2003-10-01	86.8
2004-01-01	87
2004-04-01	85.6
2004-07-01	84.3
2004-10-01	83.9
2005-01-01	83.5
2005-04-01	82.2
2005-07-01	81.4
2005-10-01	80.5
2006-01-01	80.6
2006-04-01	79
2006-07-01	78.7
2006-10-01	78.1
2007-01-01	77.9
2007-04-01	76.8
2007-07-01	76.7
2007-10-01	75.6
2008-01-01	74.8
2008-04-01	74.5
2008-07-01	72.4
2008-10-01	72.7
2009-01-01	72.6
2009-04-01	71
2009-07-01	70.1
2009-10-01	70.5
2010-01-01	68.5
2010-04-01	67.6
2010-07-01	67.5
2010-10-01	67.4
2011-01-01	67.4
2011-04-01	65.9
2011-07-01	64.6
2011-10-01	63.8
2012-01-01	62.9
2012-04-01	62
2012-07-01	61.7
2012-10-01	61.4
2013-01-01	59.9
2013-04-01	59.8
2013-07-01	59.7
2013-10-01	58.8
2014-01-01	59.5
2014-04-01	58.6
2014-07-01	57.3
2014-10-01	56
2015-01-01	55.1
2015-04-01	55.1
2015-07-01	53.9
2015-10-01	52.7
2016-01-01	53.7
2016-04-01	51.7
2016-07-01	51.4
2016-10-01	50.4
2017-01-01	48.8
2017-04-01	46.7
2017-07-01	46.9
2017-10-01	45.4
2018-01-01	46.7
2018-04-01	47.2