Quarter	Percent
1999-04-01	58.6
2000-01-01	56.2
2000-04-01	56.5
2000-07-01	57.4
2000-10-01	56.3
2001-01-01	57
2001-04-01	56.8
2001-07-01	56.6
2001-10-01	57.6
2002-01-01	57.8
2002-04-01	57.2
2002-07-01	58.5
2002-10-01	56.3
2003-01-01	56
2003-04-01	58.7
2003-07-01	60.7
2003-10-01	60.4
2004-01-01	57.8
2004-04-01	58.3
2004-07-01	58.7
2004-10-01	59.1
2005-01-01	56.7
2005-04-01	58.3
2005-07-01	60.6
2005-10-01	60.3
2006-01-01	61.6
2006-04-01	63.5
2006-07-01	64.5
2006-10-01	64.2
2007-01-01	63.8
2007-04-01	64.5
2007-07-01	65.3
2007-10-01	65
2008-01-01	65.5
2008-04-01	65
2008-07-01	64.6
2008-10-01	64.1
2009-01-01	58.4
2009-04-01	56
2009-07-01	57.7
2009-10-01	54.4
2010-01-01	50.4
2010-04-01	51.4
2010-07-01	56.1
2010-10-01	58.2
2011-01-01	57.6
2011-04-01	58
2011-07-01	61.1
2011-10-01	59.8
2012-01-01	59.1
2012-04-01	59.9
2012-07-01	62.7
2012-10-01	61.9
2013-01-01	61.1
2013-04-01	63.1
2013-07-01	62.9
2013-10-01	61.5
2014-01-01	61.7
2014-04-01	63.9
2014-07-01	63.9
2014-10-01	64.4
2015-01-01	62.9
2015-04-01	65.2
2015-07-01	67.7
2015-10-01	64.8
2016-01-01	63.3
2016-04-01	65.8
2016-07-01	67.0
2016-10-01	65.0
2017-01-01	65.9
2017-04-01	66.3
2017-07-01	67.8
2017-10-01	67.9
2018-01-01	65.7
2018-04-01	67.7