Quarter	Percent
1999-04-01	52.1
1999-07-01	51.7
1999-10-01	52
2000-01-01	52.3
2000-04-01	52.8
2000-07-01	53.2
2000-10-01	53.5
2001-01-01	53.8
2001-04-01	53.9
2001-07-01	54.2
2001-10-01	54.5
2002-01-01	54.7
2002-04-01	55.1
2002-07-01	55.4
2002-10-01	55.9
2003-01-01	56.2
2003-04-01	57.3
2003-07-01	57.6
2003-10-01	57.5
2004-01-01	57.6
2004-04-01	57.9
2004-07-01	57.5
2004-10-01	58.1
2005-01-01	58.4
2005-04-01	58.3
2005-07-01	58.3
2005-10-01	58.6
2006-01-01	58.6
2006-04-01	59
2006-07-01	59.5
2006-10-01	59.3
2007-01-01	59.0
2007-04-01	59.2
2007-07-01	59.0
2007-10-01	59.8
2008-01-01	59.6
2008-04-01	59.8
2008-07-01	59.6
2008-10-01	60.3
2009-01-01	60.5
2009-04-01	60.4
2009-07-01	60.1
2009-10-01	60.1
2010-01-01	60.4
2010-04-01	59.8
2010-07-01	60.3
2010-10-01	59.5
2011-01-01	59.9
2011-04-01	59.6
2011-07-01	59.5
2011-10-01	59.7
2012-01-01	60.5
2012-04-01	61
2012-07-01	61.2
2012-10-01	61.7
2013-01-01	62
2013-04-01	62.6
2013-07-01	63.2
2013-10-01	63.5
2014-01-01	63.7
2014-04-01	63.5
2014-07-01	63.4
2014-10-01	63.6
2015-01-01	63.9
2015-04-01	64.0
2015-07-01	64.6
2015-10-01	65.2
2016-01-01	65.5
2016-04-01	65.9
2016-07-01	65.8
2016-10-01	65.9
2017-01-01	66.4
2017-04-01	66.4
2017-07-01	66.3
2017-10-01	66.7
2018-01-01	67.3
2018-04-01	67.4