Quarter	Percent
1999-04-01	27.6
2000-01-01	28
2000-04-01	27
2000-07-01	26.5
2000-10-01	25.8
2001-01-01	25.9
2001-04-01	25.8
2001-07-01	26
2001-10-01	25.1
2002-01-01	24.4
2002-04-01	24.6
2002-07-01	24.4
2002-10-01	23.6
2003-01-01	22.9
2003-04-01	23.4
2003-07-01	23
2003-10-01	22.5
2004-01-01	22.4
2004-04-01	22
2004-07-01	22.2
2004-10-01	21.6
2005-01-01	21.4
2005-04-01	21.2
2005-07-01	21.3
2005-10-01	20.2
2006-01-01	20
2006-04-01	20.2
2006-07-01	20.2
2006-10-01	19.4
2007-01-01	19.2
2007-04-01	18.9
2007-07-01	19
2007-10-01	18.1
2008-01-01	17.8
2008-04-01	17.6
2008-07-01	17.7
2008-10-01	16.8
2009-01-01	16.6
2009-04-01	17.2
2009-07-01	17.3
2009-10-01	16.8
2010-01-01	17.7
2010-04-01	17.6
2010-07-01	17.9
2010-10-01	17.3
2011-01-01	17.7
2011-04-01	18.3
2011-07-01	18.9
2011-10-01	17.9
2012-01-01	17.8
2012-04-01	18.0
2012-07-01	17.8
2012-10-01	17.3
2013-01-01	17.2
2013-04-01	17.5
2013-07-01	17.6
2013-10-01	17.4
2014-01-01	17.9
2014-04-01	18.1
2014-07-01	18.5
2014-10-01	17.7
2015-01-01	17.5
2015-04-01	17.9
2015-07-01	18.2
2015-10-01	17.8
2016-01-01	18.0
2016-04-01	17.8
2016-07-01	17.9
2016-10-01	17.6
2017-01-01	17.7
2017-04-01	17.9
2017-07-01	18.2
2017-10-01	18.1
2018-01-01	18.1
2018-04-01	17.8