Quarter	Percent
1999-01-01	24.5
2000-01-01	20.7
2000-04-01	21.8
2000-07-01	23
2000-10-01	19.8
2001-01-01	18.2
2001-04-01	21.9
2001-07-01	22
2001-10-01	19.4
2002-01-01	18.8
2002-04-01	19.5
2002-07-01	18.2
2002-10-01	19.2
2003-01-01	19.9
2003-04-01	20.1
2003-07-01	19.4
2003-10-01	19.7
2004-01-01	18.6
2004-04-01	19.1
2004-07-01	20.3
2004-10-01	19.5
2005-01-01	17.9
2005-04-01	19.2
2005-07-01	21.4
2005-10-01	20.1
2006-01-01	17.7
2006-04-01	18.3
2006-07-01	20.6
2006-10-01	19.4
2007-01-01	18.8
2007-04-01	18.5
2007-07-01	20.1
2007-10-01	20.2
2008-01-01	19.9
2008-04-01	20.8
2008-07-01	21.1
2008-10-01	20.9
2009-01-01	20.9
2009-04-01	21.6
2009-07-01	22.2
2009-10-01	22.8
2010-01-01	22.3
2010-04-01	23.7
2010-07-01	25.2
2010-10-01	25.5
2011-01-01	26
2011-04-01	27
2011-07-01	27.8
2011-10-01	28
2012-01-01	27.7
2012-04-01	28.5
2012-07-01	30.2
2012-10-01	30.4
2013-01-01	29.7
2013-04-01	30.4
2013-07-01	31.5
2013-10-01	32.4
2014-01-01	32.2
2014-04-01	32.2
2014-07-01	33.3
2014-10-01	34
2015-01-01	34.1
2015-04-01	34.3
2015-07-01	36.5
2015-10-01	37.3
2016-01-01	36.2
2016-04-01	37.2
2016-07-01	38.4
2016-10-01	38.8
2017-01-01	38.0
2017-04-01	40.0
2017-07-01	40.7
2017-10-01	38.5
2018-01-01	38.4
2018-04-01	40.1