Quarter	Percent
1998-01-01	32.3
1998-04-01	32.9
1998-07-01	33.1
1998-10-01	32.8
1999-01-01	33.3
1999-04-01	33
1999-07-01	33
1999-10-01	32.5
2000-01-01	32.6
2000-04-01	33.5
2000-07-01	33.8
2000-10-01	33.5
2001-01-01	33.3
2001-04-01	33.3
2001-07-01	33.3
2001-10-01	32.3
2002-01-01	32.7
2002-04-01	34
2002-07-01	34.3
2002-10-01	34.1
2003-01-01	34
2003-04-01	34.9
2003-07-01	35
2003-10-01	34.6
2004-01-01	34.6
2004-04-01	35.4
2004-07-01	35.4
2004-10-01	35.3
2005-01-01	35.1
2005-04-01	35.7
2005-07-01	35.9
2005-10-01	35.9
2006-01-01	36.1
2006-04-01	36.7
2006-07-01	37.1
2006-10-01	36.5
2007-01-01	36.3
2007-04-01	37.1
2007-07-01	37.2
2007-10-01	37
2008-01-01	36.9
2008-04-01	37.8
2008-07-01	37.9
2008-10-01	37.6
2009-01-01	37.5
2009-04-01	38
2009-07-01	38
2009-10-01	37.4
2010-01-01	37
2010-04-01	37.4
2010-07-01	37.1
2010-10-01	36.1
2011-01-01	35.3
2011-04-01	34.9
2011-07-01	34.2
2011-10-01	33.1
2012-01-01	32.2
2012-04-01	31.9
2012-07-01	31.3
2012-10-01	30.9
2013-01-01	30
2013-04-01	30.3
2013-07-01	30.1
2013-10-01	29.7
2014-01-01	30.1
2014-04-01	30.7
2014-07-01	31.3
2014-10-01	31.1
2015-01-01	30.7
2015-04-01	32.1
2015-07-01	32.4
2015-10-01	32.2
2016-01-01	31.7
2016-04-01	32.7
2016-07-01	33.0
2016-10-01	32.1
2017-01-01	32.2
2017-04-01	33.7
2017-07-01	33.6
2017-10-01	32.7
2018-01-01	32.5
2018-04-01	34.1