Quarter	Percent
1999-01-01	36.7
1999-04-01	35.2
1999-07-01	35.3
1999-10-01	35.6
2000-01-01	36.8
2000-04-01	36.2
2000-07-01	34.6
2000-10-01	35.6
2001-01-01	35.5
2001-04-01	35.3
2001-07-01	34.2
2001-10-01	35.6
2002-01-01	34.5
2002-04-01	35.3
2002-07-01	36.5
2002-10-01	37.2
2003-01-01	37
2003-04-01	36.9
2003-07-01	36.8
2003-10-01	35.5
2004-01-01	35
2004-04-01	34.5
2004-07-01	33
2004-10-01	34.1
2005-01-01	34.6
2005-04-01	34.7
2005-07-01	33.4
2005-10-01	33.4
2006-01-01	34.7
2006-04-01	34.3
2006-07-01	33.6
2006-10-01	34.8
2007-01-01	34.7
2007-04-01	33.3
2007-07-01	32.7
2007-10-01	33.8
2008-01-01	35.1
2008-04-01	34.7
2008-07-01	33
2008-10-01	34.7
2009-01-01	36.4
2009-04-01	34.5
2009-07-01	33.3
2009-10-01	34
2010-01-01	34.9
2010-04-01	35.1
2010-07-01	34.5
2010-10-01	34.5
2011-01-01	36.3
2011-04-01	36.4
2011-07-01	35.9
2011-10-01	36.6
2012-01-01	37.6
2012-04-01	37.6
2012-07-01	36.5
2012-10-01	36.2
2013-01-01	37.4
2013-04-01	36.9
2013-07-01	36.5
2013-10-01	36.9
2014-01-01	37.6
2014-04-01	36.5
2014-07-01	36.3
2014-10-01	36.4
2015-01-01	37.5
2015-04-01	36.7
2015-07-01	36.2
2015-10-01	37.9
2016-01-01	39.4
2016-04-01	38.6
2016-07-01	38.4
2016-10-01	38.3
2017-01-01	37.6
2017-04-01	36.8
2017-07-01	36.1
2017-10-01	36.8
2018-01-01	36.9
2018-04-01	35.5