Quarter	Percent
2000-04-01	49.4
2001-04-01	49.2
2002-04-01	48.5
2003-04-01	46.8
2004-04-01	46.1
2005-01-01	45.4
2005-04-01	44.9
2005-07-01	44.6
2005-10-01	44.2
2006-01-01	44.7
2006-04-01	44.1
2006-07-01	43.4
2006-10-01	43.5
2007-01-01	43.9
2007-04-01	43.1
2007-07-01	42.8
2007-10-01	43.0
2008-01-01	43.0
2008-04-01	42.2
2008-07-01	42.1
2008-10-01	41.9
2009-01-01	42.1
2009-04-01	41.4
2009-07-01	41.5
2009-10-01	41.4
2010-01-01	41.6
2010-04-01	41.2
2010-07-01	41.2
2010-10-01	41.2
2011-01-01	41.2
2011-04-01	40.7
2011-07-01	40.9
2011-10-01	40.3
2012-01-01	40.2
2012-04-01	39.1
2012-07-01	38.6
2012-10-01	38.3
2013-01-01	38.5
2013-04-01	37.7
2013-07-01	37.0
2013-10-01	36.7
2014-01-01	36.8
2014-04-01	36.4
2014-07-01	35.9
2014-10-01	35.4
2015-01-01	35.8
2015-04-01	35.2
2015-07-01	34.6
2015-10-01	34.3
2016-01-01	34.1
2016-04-01	33.5
2016-07-01	33.2
2016-10-01	32.9
2017-01-01	33.2
2017-04-01	32.2
2017-07-01	31.9
2017-10-01	31.5
2018-01-01	31.7
2018-04-01	31.1