Quarter	Percent
1999-01-01	42.5
1999-04-01	42.1
1999-07-01	43.8
1999-10-01	42.6
2000-01-01	42.6
2000-04-01	41.8
2000-07-01	43.2
2000-10-01	42.6
2001-01-01	41.9
2001-04-01	41
2001-07-01	41.9
2001-10-01	40.4
2002-01-01	39.4
2002-04-01	39
2002-07-01	39.5
2002-10-01	38.9
2003-01-01	37.5
2003-04-01	36.9
2003-07-01	37.6
2003-10-01	36.8
2004-01-01	36.3
2004-04-01	35.5
2004-07-01	35.9
2004-10-01	35
2005-01-01	33.6
2005-04-01	31.7
2005-07-01	32.3
2005-10-01	32.1
2006-01-01	30.6
2006-04-01	29.9
2006-07-01	31.7
2006-10-01	31.2
2007-01-01	30.2
2007-04-01	29.8
2007-07-01	31.3
2007-10-01	29.6
2008-01-01	28.3
2008-04-01	26.6
2008-07-01	26.4
2008-10-01	25.7
2009-01-01	24.3
2009-04-01	24.1
2009-07-01	26.6
2009-10-01	26.6
2010-01-01	25.4
2010-04-01	24.7
2010-07-01	26.2
2010-10-01	25.8
2011-01-01	23.9
2011-04-01	21.9
2011-07-01	22.1
2011-10-01	22.9
2012-01-01	22.9
2012-04-01	22.7
2012-07-01	24.5
2012-10-01	24.3
2013-01-01	24.5
2013-04-01	23.3
2013-07-01	24
2013-10-01	23
2014-01-01	23.2
2014-04-01	22.2
2014-07-01	24.8
2014-10-01	24.1
2015-01-01	24.8
2015-04-01	24.1
2015-07-01	25.8
2015-10-01	24.8
2016-01-01	23.9
2016-04-01	22.7
2016-07-01	25.3
2016-10-01	26.9
2017-01-01	25.9
2017-04-01	26.2
2017-07-01	26.2
2017-10-01	27.6
2018-01-01	24.4
2018-04-01	24.3