Quarter	Percent
1999-01-01	24.2
1999-04-01	22.9
1999-07-01	23
1999-10-01	22.5
2000-01-01	21.7
2000-04-01	20.4
2000-07-01	20.4
2000-10-01	19.8
2001-01-01	15.7
2001-04-01	15.1
2001-07-01	15
2001-10-01	15.3
2002-01-01	16.4
2002-04-01	16.1
2002-07-01	16.3
2002-10-01	16.1
2003-01-01	16.8
2003-04-01	15.7
2003-07-01	15.6
2003-10-01	15.5
2004-01-01	15.6
2004-04-01	15.1
2004-07-01	14.4
2004-10-01	14.4
2005-01-01	13.5
2005-04-01	12
2005-07-01	11.1
2005-10-01	11.5
2006-01-01	12.1
2006-04-01	11.3
2006-07-01	11
2006-10-01	11.2
2007-01-01	11.3
2007-04-01	10.4
2007-07-01	10.4
2007-10-01	10.9
2008-01-01	11.9
2008-04-01	12.1
2008-07-01	12.5
2008-10-01	14.9
2009-01-01	17.8
2009-04-01	18.1
2009-07-01	18
2009-10-01	18.9
2010-01-01	20
2010-04-01	20.4
2010-07-01	20.3
2010-10-01	20.6
2011-01-01	21.8
2011-04-01	21
2011-07-01	21.9
2011-10-01	23
2012-01-01	24.6
2012-04-01	24.5
2012-07-01	25.2
2012-10-01	26.4
2013-01-01	27.4
2013-04-01	26.9
2013-07-01	26.3
2013-10-01	26.6
2014-01-01	26.7
2014-04-01	25.5
2014-07-01	25.1
2014-10-01	24.9
2015-01-01	25.1
2015-04-01	24.1
2015-07-01	22.8
2015-10-01	22.6
2016-01-01	22.9
2016-04-01	22.0
2016-07-01	20.8
2016-10-01	20.4
2017-01-01	20.6
2017-04-01	19.2
2017-07-01	18.3
2017-10-01	18.4
2018-01-01	18.7
2018-04-01	17.2
2018-07-01	16.3