Quarter	Percent
1999-01-01	32.1
1999-04-01	32
1999-07-01	35.9
1999-10-01	35.3
2000-01-01	36.8
2000-04-01	36.9
2000-07-01	37.4
2000-10-01	36.7
2001-01-01	39.4
2001-04-01	38.9
2001-07-01	39.6
2001-10-01	38.8
2002-01-01	38.9
2002-04-01	37.7
2002-07-01	37.7
2002-10-01	36.4
2003-01-01	34.7
2003-04-01	32.9
2003-07-01	34.1
2003-10-01	31.9
2004-01-01	34
2004-04-01	32.8
2004-07-01	33
2004-10-01	32.5
2005-01-01	31.6
2005-04-01	28.3
2005-07-01	30.5
2005-10-01	29.8
2006-01-01	29.2
2006-04-01	26.3
2006-07-01	27.6
2006-10-01	23.5
2007-01-01	20.4
2007-04-01	19.2
2007-07-01	21.9
2007-10-01	19.8
2008-01-01	19
2008-04-01	19.1
2008-07-01	19.4
2008-10-01	18.6
2009-01-01	22.4
2009-04-01	25.1
2009-07-01	29.3
2009-10-01	31.9
2010-01-01	33.6
2010-04-01	31.9
2010-07-01	34.3
2010-10-01	34.2
2011-01-01	33.3
2011-04-01	31.9
2011-07-01	33.8
2011-10-01	34.7
2012-01-01	33.7
2012-04-01	31.7
2012-07-01	34.4
2012-10-01	36.1
2013-01-01	34.4
2013-04-01	32.3
2013-07-01	33.7
2013-10-01	34.3
2014-01-01	32.1
2014-04-01	29.2
2014-07-01	30
2014-10-01	27.5
2015-01-01	26.4
2015-04-01	25.3
2015-07-01	27.9
2015-10-01	26.2
2016-01-01	24.3
2016-04-01	20.6
2016-07-01	22.7
2016-10-01	21.3
2017-01-01	18.7
2017-04-01	17.7
2017-07-01	19.7
2017-10-01	19.5
2018-01-01	17.1
2018-04-01	13.7