Quarter	Percent
1999-01-01	34.9
2000-01-01	35.5
2001-01-01	36.9
2002-01-01	40.5
2003-01-01	41.8
2003-04-01	42.3
2003-07-01	43.2
2003-10-01	43.8
2004-01-01	44.5
2004-04-01	43.9
2004-07-01	43.3
2004-10-01	43.2
2005-01-01	43.8
2005-04-01	43.9
2005-07-01	43.2
2005-10-01	43.4
2006-01-01	43.1
2006-04-01	43.2
2006-07-01	42.3
2006-10-01	42.4
2007-01-01	42.9
2007-04-01	42.9
2007-07-01	42.3
2007-10-01	41.8
2008-01-01	41.9
2008-04-01	42.6
2008-07-01	42.2
2008-10-01	42.9
2009-01-01	43.2
2009-04-01	44.5
2009-07-01	43.9
2009-10-01	44.5
2010-01-01	44.3
2010-04-01	45.2
2010-07-01	45.2
2010-10-01	45.3
2011-01-01	45.6
2011-04-01	46.4
2011-07-01	46.8
2011-10-01	48.2
2012-01-01	49.0
2012-04-01	50.3
2012-07-01	51.3
2012-10-01	52.6
2013-01-01	52.2
2013-04-01	52.6
2013-07-01	52.2
2013-10-01	52.4
2014-01-01	52.8
2014-04-01	52.7
2014-07-01	52.6
2014-10-01	54.3
2015-01-01	54.2
2015-04-01	55.4
2015-07-01	55.3
2015-10-01	55.6
2016-01-01	55.7
2016-04-01	55.9
2016-07-01	56.4
2016-10-01	56.5
2017-01-01	56.0
2017-04-01	56.9
2017-07-01	56.6
2017-10-01	58.1
2018-01-01	57.7
2018-04-01	58.2