Quarter	Percent
1999-01-01	33.8
1999-04-01	33.1
1999-07-01	37.5
1999-10-01	36.7
2000-01-01	39.8
2000-04-01	40
2000-07-01	39.9
2000-10-01	39.1
2001-01-01	43.3
2001-04-01	42.6
2001-07-01	41.4
2001-10-01	41
2002-01-01	42
2002-04-01	38.8
2002-07-01	39.5
2002-10-01	37.5
2003-01-01	37
2003-04-01	34.8
2003-07-01	34.3
2003-10-01	33.1
2004-01-01	36.6
2004-04-01	34.8
2004-07-01	33.7
2004-10-01	33.8
2005-01-01	32.9
2005-04-01	29.7
2005-07-01	30.6
2005-10-01	30.8
2006-01-01	29.4
2006-04-01	26.1
2006-07-01	26.6
2006-10-01	23.4
2007-01-01	21.3
2007-04-01	20.7
2007-07-01	21.2
2007-10-01	18.6
2008-01-01	18.8
2008-04-01	20
2008-07-01	17.9
2008-10-01	17.3
2009-01-01	22.1
2009-04-01	26.5
2009-07-01	29.1
2009-10-01	33.1
2010-01-01	35.5
2010-04-01	33
2010-07-01	35.2
2010-10-01	34.8
2011-01-01	33.8
2011-04-01	32
2011-07-01	33
2011-10-01	34
2012-01-01	35.1
2012-04-01	33
2012-07-01	34.3
2012-10-01	37.4
2013-01-01	38.2
2013-04-01	33.7
2013-07-01	33.1
2013-10-01	34.6
2014-01-01	31.8
2014-04-01	27.7
2014-07-01	29.7
2014-10-01	28.6
2015-01-01	26.5
2015-04-01	24.9
2015-07-01	27.2
2015-10-01	24.5
2016-01-01	22.4
2016-04-01	17.7
2016-07-01	20.1
2016-10-01	18.8
2017-01-01	17.6
2017-04-01	17.9
2017-07-01	19.1
2017-10-01	17.9
2018-01-01	17.5
2018-04-01	12.7