Quarter	Percent
1999-01-01	40.5
1999-04-01	39.8
1999-07-01	40.2
1999-10-01	39.8
2000-01-01	38.7
2000-04-01	37.8
2000-07-01	38.5
2000-10-01	38.3
2001-01-01	36
2001-04-01	34.1
2001-07-01	34.7
2001-10-01	33.7
2002-01-01	32.6
2002-04-01	32.3
2002-07-01	33.1
2002-10-01	32.5
2003-01-01	32.1
2003-04-01	30.6
2003-07-01	31.2
2003-10-01	29.9
2004-01-01	28.8
2004-04-01	27.3
2004-07-01	27.8
2004-10-01	27.9
2005-01-01	27.4
2005-04-01	26.5
2005-07-01	27.3
2005-10-01	27.1
2006-01-01	26
2006-04-01	25.7
2006-07-01	27.8
2006-10-01	27.3
2007-01-01	25.9
2007-04-01	25
2007-07-01	26.4
2007-10-01	25.6
2008-01-01	24.6
2008-04-01	24.2
2008-07-01	26.3
2008-10-01	25.4
2009-01-01	23.7
2009-04-01	24.3
2009-07-01	25.5
2009-10-01	25.2
2010-01-01	24.5
2010-04-01	24.3
2010-07-01	25.3
2010-10-01	25.2
2011-01-01	24.1
2011-04-01	23.7
2011-07-01	25.2
2011-10-01	24.2
2012-01-01	23.8
2012-04-01	24.5
2012-07-01	27
2012-10-01	27.4
2013-01-01	26.3
2013-04-01	26.4
2013-07-01	28.8
2013-10-01	28.2
2014-01-01	28.6
2014-04-01	29.1
2014-07-01	30.3
2014-10-01	30.1
2015-01-01	29.7
2015-04-01	30.7
2015-07-01	32.1
2015-10-01	31.7
2016-01-01	31.2
2016-04-01	31.6
2016-07-01	33.3
2016-10-01	33.1
2017-01-01	31.7
2017-04-01	32.4
2017-07-01	33.0
2017-10-01	32.7
2018-01-01	30.9
2018-04-01	31.8