Quarter	Percent
1998-01-01	47.3
1998-04-01	46.5
1998-07-01	46.6
1998-10-01	47.2
1999-01-01	45.9
1999-04-01	46.6
1999-07-01	47.6
1999-10-01	49.5
2000-01-01	47.9
2000-04-01	46.9
2000-07-01	48.6
2000-10-01	49.0
2001-01-01	48.5
2001-04-01	48.1
2001-07-01	49.5
2001-10-01	48.4
2002-01-01	47.9
2002-04-01	47.6
2002-07-01	47.9
2002-10-01	47.4
2003-01-01	44.7
2003-04-01	43
2003-07-01	42.5
2003-10-01	40.9
2004-01-01	40.5
2004-04-01	41.2
2004-07-01	41.5
2004-10-01	40.3
2005-01-01	39.8
2005-04-01	39.9
2005-07-01	39.9
2005-10-01	38.9
2006-01-01	38.9
2006-04-01	39.3
2006-07-01	38.8
2006-10-01	37.9
2007-01-01	37.7
2007-04-01	38.3
2007-07-01	39.6
2007-10-01	38.5
2008-01-01	38.7
2008-04-01	38.5
2008-07-01	37.1
2008-10-01	36.4
2009-01-01	33.2
2009-04-01	32.4
2009-07-01	33.1
2009-10-01	31.1
2010-01-01	29.8
2010-04-01	29.5
2010-07-01	29.6
2010-10-01	30.1
2011-01-01	29.3
2011-04-01	28.1
2011-07-01	30.3
2011-10-01	27
2012-01-01	24.9
2012-04-01	25
2012-07-01	25.8
2012-10-01	23.4
2013-01-01	21.8
2013-04-01	22.9
2013-07-01	23.8
2013-10-01	23.1
2014-01-01	21.9
2014-04-01	21.2
2014-07-01	25.8
2014-10-01	22.6
2015-01-01	23.4
2015-04-01	23.4
2015-07-01	25.3
2015-10-01	24.3
2016-01-01	23.7
2016-04-01	25.5
2016-07-01	27.0
2016-10-01	25.8
2017-01-01	26.8
2017-04-01	26.4
2017-07-01	28.6
2017-10-01	28.5
2018-01-01	27.3
2018-04-01	28.8