Quarter	Percent
1999-04-01	49.8
2000-01-01	49.3
2000-04-01	50.8
2000-07-01	51.8
2000-10-01	52.7
2001-01-01	51.8
2001-04-01	51.4
2001-07-01	51.3
2001-10-01	53
2002-01-01	53.7
2002-04-01	56.2
2002-07-01	56.6
2002-10-01	56.7
2003-01-01	58.2
2003-04-01	58.2
2003-07-01	58.2
2003-10-01	58.3
2004-01-01	59
2004-04-01	58.7
2004-07-01	59.2
2004-10-01	59.7
2005-01-01	59.2
2005-04-01	59.7
2005-07-01	59.8
2005-10-01	59.3
2006-01-01	58.7
2006-04-01	60.4
2006-07-01	60.9
2006-10-01	61.7
2007-01-01	63.2
2007-04-01	64
2007-07-01	64.5
2007-10-01	64.4
2008-01-01	64.8
2008-04-01	65.5
2008-07-01	66.3
2008-10-01	66.9
2009-01-01	67.3
2009-04-01	67.5
2009-07-01	67.9
2009-10-01	67.7
2010-01-01	66.8
2010-04-01	67.6
2010-07-01	67.7
2010-10-01	67.3
2011-01-01	66.4
2011-04-01	67.2
2011-07-01	67.8
2011-10-01	68.8
2012-01-01	69.7
2012-04-01	70.7
2012-07-01	70.7
2012-10-01	71.4
2013-01-01	72.5
2013-04-01	73.8
2013-07-01	75.0
2013-10-01	75.7
2014-01-01	74.9
2014-04-01	75.4
2014-07-01	75.4
2014-10-01	76.2
2015-01-01	77.4
2015-04-01	77.8
2015-07-01	77.1
2015-10-01	78.3
2016-01-01	78.5
2016-04-01	78.2
2016-07-01	77.5
2016-10-01	78.8
2017-01-01	78.7
2017-04-01	79.2
2017-07-01	78.7
2017-10-01	79.3
2018-01-01	79.1
2018-04-01	79.8