Quarter	Percent
1999-04-01	55.9
2000-04-01	57.1
2001-04-01	57.2
2002-04-01	56.8
2003-04-01	54.9
2004-04-01	52.5
2005-01-01	49.1
2005-04-01	48.2
2005-07-01	47.7
2005-10-01	46.6
2006-01-01	46.3
2006-04-01	45.5
2006-07-01	44.9
2006-10-01	43.6
2007-01-01	44.2
2007-04-01	42.4
2007-07-01	42.7
2007-10-01	41.9
2008-01-01	42.4
2008-04-01	40.9
2008-07-01	41.2
2008-10-01	40.6
2009-01-01	40
2009-04-01	38.6
2009-07-01	39.5
2009-10-01	38.1
2010-01-01	37.2
2010-04-01	37.6
2010-07-01	37.7
2010-10-01	37.2
2011-01-01	36.5
2011-04-01	35.8
2011-07-01	35.8
2011-10-01	35.4
2012-01-01	35.3
2012-04-01	35
2012-07-01	34.1
2012-10-01	33.9
2013-01-01	33.5
2013-04-01	33
2013-07-01	32.2
2013-10-01	31.5
2014-01-01	31.3
2014-04-01	31.2
2014-07-01	30.7
2014-10-01	30.5
2015-01-01	31.0
2015-04-01	31.1
2015-07-01	30.3
2015-10-01	29.9
2016-01-01	29.3
2016-04-01	28.8
2016-07-01	28.4
2016-10-01	28.1
2017-01-01	28.5
2017-04-01	27.4
2017-07-01	27.1
2017-10-01	26.6
2018-01-01	27.2
2018-04-01	26.9