Quarter	Percent
1999-01-01	33
1999-04-01	32.5
1999-07-01	32
1999-10-01	32.2
2000-01-01	32.9
2000-04-01	32.4
2000-07-01	31.7
2000-10-01	31.6
2001-01-01	32.8
2001-04-01	32.8
2001-07-01	32.5
2001-10-01	32.9
2002-01-01	33.4
2002-04-01	33.1
2002-07-01	32.5
2002-10-01	32.6
2003-01-01	33.1
2003-04-01	32.3
2003-07-01	31.9
2003-10-01	32.3
2004-01-01	32.9
2004-04-01	32.9
2004-07-01	32.6
2004-10-01	32.6
2005-01-01	32.8
2005-04-01	32.3
2005-07-01	31.5
2005-10-01	31.7
2006-01-01	31.9
2006-04-01	31
2006-07-01	30.8
2006-10-01	30.7
2007-01-01	31.6
2007-04-01	31.2
2007-07-01	31
2007-10-01	31.6
2008-01-01	32.6
2008-04-01	32.1
2008-07-01	31.3
2008-10-01	32.1
2009-01-01	32.8
2009-04-01	32.1
2009-07-01	32
2009-10-01	32.2
2010-01-01	32.8
2010-04-01	32.2
2010-07-01	31.8
2010-10-01	32.1
2011-01-01	32.5
2011-04-01	31.7
2011-07-01	31
2011-10-01	31.3
2012-01-01	31.5
2012-04-01	30.6
2012-07-01	29.8
2012-10-01	29.8
2013-01-01	30.6
2013-04-01	29.1
2013-07-01	28
2013-10-01	28.3
2014-01-01	27.6
2014-04-01	26.8
2014-07-01	25.8
2014-10-01	26.1
2015-01-01	26.0
2015-04-01	24.8
2015-07-01	24.0
2015-10-01	24.1
2016-01-01	24.0
2016-04-01	23.0
2016-07-01	22.6
2016-10-01	22.6
2017-01-01	22.8
2017-04-01	21.7
2017-07-01	21.2
2017-10-01	21.3
2018-01-01	21.4
2018-04-01	21.1