Quarter	Percent
1998-01-01	34.4
1998-04-01	34.7
1998-07-01	35.1
1998-10-01	34.1
1999-01-01	32.1
1999-04-01	32.3
1999-07-01	32.5
1999-10-01	32.7
2000-01-01	32.2
2000-04-01	32.6
2000-07-01	32.9
2000-10-01	33
2001-01-01	29.6
2001-04-01	30.7
2001-07-01	31.3
2001-10-01	30.4
2002-01-01	31
2002-04-01	31.9
2002-07-01	31.5
2002-10-01	30.6
2003-01-01	31.4
2003-04-01	31.5
2003-07-01	30.1
2003-10-01	28.8
2004-01-01	32.7
2004-04-01	32.8
2004-07-01	31.9
2004-10-01	31.3
2005-01-01	31
2005-04-01	30.4
2005-07-01	29.1
2005-10-01	29.3
2006-01-01	30.5
2006-04-01	30
2006-07-01	29.3
2006-10-01	28
2007-01-01	28.9
2007-04-01	29.5
2007-07-01	29.8
2007-10-01	28.2
2008-01-01	27.4
2008-04-01	28.7
2008-07-01	29.1
2008-10-01	27.8
2009-01-01	27.5
2009-04-01	27.5
2009-07-01	28.3
2009-10-01	25.9
2010-01-01	25.1
2010-04-01	24.9
2010-07-01	24.6
2010-10-01	22.1
2011-01-01	20.8
2011-04-01	19.7
2011-07-01	19.4
2011-10-01	17.6
2012-01-01	16.9
2012-04-01	16.5
2012-07-01	15.9
2012-10-01	15.1
2013-01-01	14.3
2013-04-01	14.2
2013-07-01	15
2013-10-01	14.8
2014-01-01	14.1
2014-04-01	15.7
2014-07-01	17.4
2014-10-01	15.9
2015-01-01	15.3
2015-04-01	15.2
2015-07-01	15.4
2015-10-01	14.7
2016-01-01	13.7
2016-04-01	14.2
2016-07-01	15.8
2016-10-01	15.1
2017-01-01	15.1
2017-04-01	16.1
2017-07-01	17.1
2017-10-01	15.2
2018-01-01	15.0
2018-04-01	16.3