Quarter	Percent
1999-01-01	47
1999-04-01	45.8
1999-07-01	47.6
1999-10-01	46.8
2000-01-01	46.1
2000-04-01	44.8
2000-07-01	46.7
2000-10-01	46.3
2001-01-01	45.5
2001-04-01	45.3
2001-07-01	46.4
2001-10-01	44.9
2002-01-01	43.7
2002-04-01	42.8
2002-07-01	43.6
2002-10-01	43.4
2003-01-01	41.7
2003-04-01	40.7
2003-07-01	41.4
2003-10-01	40.5
2004-01-01	39.8
2004-04-01	39.1
2004-07-01	39.5
2004-10-01	38.7
2005-01-01	37.3
2005-04-01	36
2005-07-01	36.5
2005-10-01	36.9
2006-01-01	35.5
2006-04-01	34.9
2006-07-01	36
2006-10-01	35.1
2007-01-01	34
2007-04-01	33.8
2007-07-01	35.5
2007-10-01	35.2
2008-01-01	33.7
2008-04-01	32
2008-07-01	32.3
2008-10-01	31.6
2009-01-01	30.4
2009-04-01	30.1
2009-07-01	32.5
2009-10-01	32.7
2010-01-01	30.6
2010-04-01	30.2
2010-07-01	31.8
2010-10-01	31.7
2011-01-01	30.4
2011-04-01	30.1
2011-07-01	29.6
2011-10-01	30.2
2012-01-01	30.2
2012-04-01	29.4
2012-07-01	31.3
2012-10-01	31.2
2013-01-01	31.5
2013-04-01	30.5
2013-07-01	30.9
2013-10-01	30.2
2014-01-01	30.8
2014-04-01	29.9
2014-07-01	31.6
2014-10-01	31.6
2015-01-01	32.0
2015-04-01	30.5
2015-07-01	32.5
2015-10-01	32.0
2016-01-01	31.5
2016-04-01	30.5
2016-07-01	33.3
2016-10-01	34.3
2017-01-01	33.4
2017-04-01	32.8
2017-07-01	32.9
2017-10-01	33.6
2018-01-01	32.0
2018-04-01	32.0