Quarter	Percent
1999-01-01	40.8
1999-04-01	40.4
1999-07-01	39.8
1999-10-01	39.9
2000-01-01	40.4
2000-04-01	40.1
2000-07-01	39.5
2000-10-01	39.4
2001-01-01	40.4
2001-04-01	40.6
2001-07-01	40.1
2001-10-01	40.5
2002-01-01	40.7
2002-04-01	40.5
2002-07-01	40
2002-10-01	40
2003-01-01	40.1
2003-04-01	39.4
2003-07-01	39
2003-10-01	39.2
2004-01-01	39.7
2004-04-01	39.8
2004-07-01	39.4
2004-10-01	39.2
2005-01-01	39.3
2005-04-01	38.8
2005-07-01	38.2
2005-10-01	38.3
2006-01-01	38.4
2006-04-01	38
2006-07-01	37.7
2006-10-01	37.7
2007-01-01	38.5
2007-04-01	38.4
2007-07-01	38.1
2007-10-01	38.4
2008-01-01	39.3
2008-04-01	39.1
2008-07-01	38.3
2008-10-01	38.6
2009-01-01	39.2
2009-04-01	38.8
2009-07-01	38.6
2009-10-01	38.5
2010-01-01	38.6
2010-04-01	38.1
2010-07-01	37.7
2010-10-01	38
2011-01-01	38.3
2011-04-01	37.7
2011-07-01	37.2
2011-10-01	37.3
2012-01-01	37.3
2012-04-01	36.5
2012-07-01	35.6
2012-10-01	35.8
2013-01-01	36.5
2013-04-01	35.4
2013-07-01	34.7
2013-10-01	34.6
2014-01-01	33.9
2014-04-01	33.2
2014-07-01	32.4
2014-10-01	32.6
2015-01-01	32.3
2015-04-01	31.5
2015-07-01	30.7
2015-10-01	30.9
2016-01-01	30.8
2016-04-01	30.0
2016-07-01	29.4
2016-10-01	29.3
2017-01-01	29.7
2017-04-01	28.9
2017-07-01	28.3
2017-10-01	28.4
2018-01-01	28.6
2018-04-01	28.1