Quarter	Percent
1999-01-01	74.8
1999-04-01	75.2
1999-07-01	76
1999-10-01	75.7
2000-01-01	75.4
2000-04-01	75.4
2000-07-01	76.2
2000-10-01	75.7
2001-01-01	75.3
2001-04-01	74.6
2001-07-01	74.3
2001-10-01	73.9
2002-01-01	73.3
2002-04-01	73.6
2002-07-01	73.1
2002-10-01	72.3
2003-01-01	72.8
2003-04-01	71.9
2003-07-01	70.8
2003-10-01	70.6
2004-01-01	70
2004-04-01	68.9
2004-07-01	67.4
2004-10-01	67
2005-01-01	66.4
2005-04-01	65.6
2005-07-01	64.3
2005-10-01	63.7
2006-01-01	63.8
2006-04-01	63.6
2006-07-01	63
2006-10-01	62.9
2007-01-01	62.5
2007-04-01	61.7
2007-07-01	60.4
2007-10-01	60.2
2008-01-01	59.4
2008-04-01	58.8
2008-07-01	56.9
2008-10-01	57.3
2009-01-01	58
2009-04-01	57.4
2009-07-01	56.5
2009-10-01	56.8
2010-01-01	55.3
2010-04-01	54.5
2010-07-01	54.8
2010-10-01	55.1
2011-01-01	55.3
2011-04-01	54.2
2011-07-01	53.5
2011-10-01	53.2
2012-01-01	52.6
2012-04-01	51.4
2012-07-01	51.5
2012-10-01	50.5
2013-01-01	50.5
2013-04-01	50.3
2013-07-01	50.5
2013-10-01	50.8
2014-01-01	51
2014-04-01	50.3
2014-07-01	49.5
2014-10-01	48.9
2015-01-01	48.8
2015-04-01	48.9
2015-07-01	48.0
2015-10-01	47.1
2016-01-01	47.5
2016-04-01	45.4
2016-07-01	46.2
2016-10-01	45.4
2017-01-01	44.9
2017-04-01	43.6
2017-07-01	43.5
2017-10-01	42.6
2018-01-01	43.0
2018-04-01	43.5