Quarter	Percent
1998-01-01	32.4
1998-04-01	33.1
1998-07-01	34.6
1998-10-01	35.6
1999-01-01	33.4
1999-04-01	33.8
1999-07-01	34.4
1999-10-01	34.3
2000-01-01	33.2
2000-04-01	34
2000-07-01	35.2
2000-10-01	34.8
2001-01-01	32.7
2001-04-01	32.5
2001-07-01	32.6
2001-10-01	32.7
2002-01-01	31
2002-04-01	30.9
2002-07-01	31.2
2002-10-01	30.9
2003-01-01	29.9
2003-04-01	30.1
2003-07-01	30.9
2003-10-01	28.5
2004-01-01	31.7
2004-04-01	31.9
2004-07-01	32.3
2004-10-01	31.1
2005-01-01	28.9
2005-04-01	28.1
2005-07-01	28.5
2005-10-01	29.5
2006-01-01	28.5
2006-04-01	26.1
2006-07-01	25.9
2006-10-01	26.9
2007-01-01	24.8
2007-04-01	25.1
2007-07-01	25.9
2007-10-01	26
2008-01-01	26
2008-04-01	25.5
2008-07-01	25.5
2008-10-01	25.1
2009-01-01	24.4
2009-04-01	23.6
2009-07-01	22.9
2009-10-01	23.8
2010-01-01	23.2
2010-04-01	23
2010-07-01	22.4
2010-10-01	24
2011-01-01	22.7
2011-04-01	21.9
2011-07-01	22.1
2011-10-01	24.4
2012-01-01	24.1
2012-04-01	23.4
2012-07-01	23.8
2012-10-01	24.7
2013-01-01	23.7
2013-04-01	22.7
2013-07-01	23.1
2013-10-01	24.1
2014-01-01	22.9
2014-04-01	23
2014-07-01	23.2
2014-10-01	23.3
2015-01-01	21.8
2015-04-01	21.6
2015-07-01	21.1
2015-10-01	22.2
2016-01-01	22.1
2016-04-01	23.0
2016-07-01	22.8
2016-10-01	23.1
2017-01-01	22.1
2017-04-01	22.0
2017-07-01	22.3
2017-10-01	22.0
2018-01-01	22.2
2018-04-01	21.7