Quarter	Percent
1999-01-01	41.8
2000-01-01	37.3
2000-04-01	37.4
2000-07-01	37.1
2000-10-01	34.9
2001-01-01	34.4
2001-04-01	36.5
2001-07-01	36
2001-10-01	35.4
2002-01-01	34.6
2002-04-01	34.9
2002-07-01	34.5
2002-10-01	34.2
2003-01-01	34.4
2003-04-01	35.3
2003-07-01	35.8
2003-10-01	35.3
2004-01-01	33.6
2004-04-01	34.3
2004-07-01	34.1
2004-10-01	34.6
2005-01-01	34.2
2005-04-01	35.5
2005-07-01	37
2005-10-01	36.8
2006-01-01	36.8
2006-04-01	37.5
2006-07-01	39.7
2006-10-01	39.6
2007-01-01	39.7
2007-04-01	41.5
2007-07-01	42
2007-10-01	42.5
2008-01-01	42.6
2008-04-01	44.4
2008-07-01	44.6
2008-10-01	44.6
2009-01-01	43.4
2009-04-01	43.3
2009-07-01	45.7
2009-10-01	44.7
2010-01-01	44.3
2010-04-01	44.2
2010-07-01	45.9
2010-10-01	46.5
2011-01-01	46.3
2011-04-01	47.5
2011-07-01	48.9
2011-10-01	48.6
2012-01-01	47.3
2012-04-01	49.3
2012-07-01	50.1
2012-10-01	50.2
2013-01-01	49.4
2013-04-01	50.6
2013-07-01	52.4
2013-10-01	52.8
2014-01-01	51
2014-04-01	52.3
2014-07-01	54.5
2014-10-01	54.7
2015-01-01	52.8
2015-04-01	52.7
2015-07-01	55.2
2015-10-01	55.9
2016-01-01	54.8
2016-04-01	54.4
2016-07-01	55.9
2016-10-01	57.6
2017-01-01	57.0
2017-04-01	57.4
2017-07-01	59.1
2017-10-01	59.7
2018-01-01	57.9
2018-04-01	59.7