Quarter	Percent
1999-04-01	66.2
2000-04-01	66.6
2001-04-01	66.4
2002-04-01	66.2
2003-04-01	64.2
2004-04-01	62.1
2005-01-01	57.8
2005-04-01	57.1
2005-07-01	57
2005-10-01	55.3
2006-01-01	54.6
2006-04-01	54.3
2006-07-01	53.7
2006-10-01	52.1
2007-01-01	52.8
2007-04-01	50.8
2007-07-01	51
2007-10-01	49.9
2008-01-01	50.6
2008-04-01	49.2
2008-07-01	49.4
2008-10-01	48.7
2009-01-01	48.1
2009-04-01	46.7
2009-07-01	47.5
2009-10-01	46.2
2010-01-01	45.1
2010-04-01	45.9
2010-07-01	45.5
2010-10-01	45.1
2011-01-01	43.7
2011-04-01	43.4
2011-07-01	42.9
2011-10-01	42.9
2012-01-01	42.6
2012-04-01	42.1
2012-07-01	41.4
2012-10-01	41.3
2013-01-01	39.9
2013-04-01	39.7
2013-07-01	38.8
2013-10-01	38.4
2014-01-01	37.9
2014-04-01	37.1
2014-07-01	36.8
2014-10-01	36.6
2015-01-01	36.5
2015-04-01	36.4
2015-07-01	36.1
2015-10-01	35.7
2016-01-01	34.9
2016-04-01	34.1
2016-07-01	33.7
2016-10-01	33.7
2017-01-01	33.2
2017-04-01	32.6
2017-07-01	32.5
2017-10-01	31.9
2018-01-01	32.0
2018-04-01	31.9