Quarter	Percent
1999-01-01	50.7
1999-04-01	50.4
1999-07-01	49.8
1999-10-01	48.9
2000-01-01	48.5
2000-04-01	48.2
2000-07-01	47.8
2000-10-01	47.5
2001-01-01	49.5
2001-04-01	49.6
2001-07-01	49
2001-10-01	48.5
2002-01-01	47.1
2002-04-01	46.3
2002-07-01	45.9
2002-10-01	45.5
2003-01-01	45
2003-04-01	44.5
2003-07-01	43.9
2003-10-01	43.5
2004-01-01	43.2
2004-04-01	42.9
2004-07-01	42.5
2004-10-01	41.9
2005-01-01	41.8
2005-04-01	41
2005-07-01	41.2
2005-10-01	40.5
2006-01-01	39.9
2006-04-01	39.3
2006-07-01	39.5
2006-10-01	38.6
2007-01-01	38.5
2007-04-01	38.3
2007-07-01	38
2007-10-01	37.6
2008-01-01	37.3
2008-04-01	36.6
2008-07-01	36.4
2008-10-01	35.4
2009-01-01	35.1
2009-04-01	34.9
2009-07-01	34.9
2009-10-01	34.7
2010-01-01	34.2
2010-04-01	33.9
2010-07-01	33.7
2010-10-01	33.3
2011-01-01	33.2
2011-04-01	32.4
2011-07-01	32.6
2011-10-01	32.5
2012-01-01	31.8
2012-04-01	31.7
2012-07-01	31.6
2012-10-01	31.4
2013-01-01	31.2
2013-04-01	31.3
2013-07-01	31.4
2013-10-01	31.1
2014-01-01	31.2
2014-04-01	31.2
2014-07-01	31.6
2014-10-01	30.8
2015-01-01	31.2
2015-04-01	30.5
2015-07-01	31.3
2015-10-01	30.8
2016-01-01	30.9
2016-04-01	30.5
2016-07-01	30.8
2016-10-01	31.0
2017-01-01	31.2
2017-04-01	31.2
2017-07-01	31.3
2017-10-01	31.0
2018-01-01	31.5
2018-04-01	31.1
2018-07-01	31.6