Quarter	Percent
1998-04-01	35.7
1999-01-01	37.7
1999-04-01	35.5
1999-07-01	41.9
1999-10-01	38.5
2000-01-01	37.1
2000-04-01	38.7
2000-07-01	40.8
2000-10-01	38.1
2001-01-01	37.9
2001-04-01	37.2
2001-07-01	45.2
2001-10-01	38.3
2002-01-01	35.9
2002-04-01	37.3
2002-07-01	41.7
2002-10-01	40.6
2003-01-01	36.5
2003-04-01	38.1
2003-07-01	39.1
2003-10-01	40.1
2004-01-01	37
2004-04-01	35.8
2004-07-01	39.8
2004-10-01	37.9
2005-01-01	37.9
2005-04-01	34.8
2005-07-01	39.1
2005-10-01	38.8
2006-01-01	39.1
2006-04-01	35.9
2006-07-01	35.8
2006-10-01	38.8
2007-01-01	35.8
2007-04-01	35.2
2007-07-01	36.8
2007-10-01	36.6
2008-01-01	35.8
2008-04-01	34.4
2008-07-01	37.4
2008-10-01	36.3
2009-01-01	34.1
2009-04-01	34.4
2009-07-01	34.8
2009-10-01	36.2
2010-01-01	33
2010-04-01	34.5
2010-07-01	37.7
2010-10-01	35.6
2011-01-01	34
2011-04-01	31.9
2011-07-01	34.6
2011-10-01	36
2012-01-01	34.6
2012-04-01	34.8
2012-07-01	34.1
2012-10-01	36.3
2013-01-01	32.5
2013-04-01	34.2
2013-07-01	34.7
2013-10-01	33.2
2014-01-01	31.7
2014-04-01	30.6
2014-07-01	33.5
2014-10-01	33.3
2015-01-01	33.5
2015-04-01	31.4
2015-07-01	33.4
2015-10-01	32.9
2016-01-01	30.6
2016-04-01	30.5
2016-07-01	30.4
2016-10-01	31.3
2017-01-01	29.5
2017-04-01	29.0
2017-07-01	34.2
2017-10-01	29.9
2018-01-01	28.3
2018-04-01	30.5