Quarter	Percent
1999-01-01	57.5
2000-01-01	54.6
2000-04-01	55.1
2000-07-01	55.5
2000-10-01	54.7
2001-01-01	53.3
2001-04-01	53.7
2001-07-01	53.8
2001-10-01	52.6
2002-01-01	51.3
2002-04-01	51.7
2002-07-01	51.7
2002-10-01	51.2
2003-01-01	50.4
2003-04-01	51.4
2003-07-01	51.6
2003-10-01	51.4
2004-01-01	50.5
2004-04-01	51.4
2004-07-01	52.3
2004-10-01	52.4
2005-01-01	51.5
2005-04-01	52.2
2005-07-01	53.7
2005-10-01	53.7
2006-01-01	52.6
2006-04-01	53.9
2006-07-01	55.6
2006-10-01	55.7
2007-01-01	55.4
2007-04-01	56.8
2007-07-01	57.8
2007-10-01	58.1
2008-01-01	58
2008-04-01	58.9
2008-07-01	60
2008-10-01	60
2009-01-01	58.9
2009-04-01	59.3
2009-07-01	59.9
2009-10-01	59.4
2010-01-01	57.9
2010-04-01	59
2010-07-01	59.7
2010-10-01	59.2
2011-01-01	58.5
2011-04-01	59.4
2011-07-01	59.8
2011-10-01	59.5
2012-01-01	58.8
2012-04-01	59.7
2012-07-01	60.2
2012-10-01	60
2013-01-01	58.7
2013-04-01	59.8
2013-07-01	60.7
2013-10-01	60.8
2014-01-01	60.3
2014-04-01	61.3
2014-07-01	62.5
2014-10-01	62.6
2015-01-01	61.9
2015-04-01	62.6
2015-07-01	63.5
2015-10-01	63.7
2016-01-01	63.7
2016-04-01	64.3
2016-07-01	64.9
2016-10-01	65.1
2017-01-01	65.4
2017-04-01	66.2
2017-07-01	66.5
2017-10-01	66.4
2018-01-01	66.6
2018-04-01	67.7