Quarter	Percent
1999-01-01	61.4
1999-04-01	62.4
1999-07-01	62.9
1999-10-01	63.1
2000-01-01	62
2000-04-01	62.7
2000-07-01	63.6
2000-10-01	63.9
2001-01-01	62.6
2001-04-01	62.9
2001-07-01	63.4
2001-10-01	62.9
2002-01-01	62.3
2002-04-01	62.9
2002-07-01	63.4
2002-10-01	63.2
2003-01-01	62.3
2003-04-01	63.5
2003-07-01	64.1
2003-10-01	63.9
2004-01-01	62.8
2004-04-01	63.1
2004-07-01	63.4
2004-10-01	63.3
2005-01-01	62.5
2005-04-01	63
2005-07-01	63.7
2005-10-01	63.4
2006-01-01	62.9
2006-04-01	64.2
2006-07-01	64.3
2006-10-01	64.3
2007-01-01	63.3
2007-04-01	64
2007-07-01	64.3
2007-10-01	63.2
2008-01-01	62.2
2008-04-01	62.9
2008-07-01	63.5
2008-10-01	62.3
2009-01-01	60.4
2009-04-01	61.2
2009-07-01	60.8
2009-10-01	60.5
2010-01-01	58.6
2010-04-01	59.8
2010-07-01	60.7
2010-10-01	60.4
2011-01-01	59.2
2011-04-01	60.8
2011-07-01	61.6
2011-10-01	61.3
2012-01-01	60
2012-04-01	61.4
2012-07-01	62.6
2012-10-01	62.6
2013-01-01	60.8
2013-04-01	63.7
2013-07-01	65
2013-10-01	65.3
2014-01-01	66.5
2014-04-01	67.3
2014-07-01	68.9
2014-10-01	68.6
2015-01-01	68.3
2015-04-01	70.1
2015-07-01	71.3
2015-10-01	71.4
2016-01-01	71.5
2016-04-01	72.9
2016-07-01	73.6
2016-10-01	73.9
2017-01-01	73.8
2017-04-01	75.1
2017-07-01	75.9
2017-10-01	76.1
2018-01-01	75.8
2018-04-01	76.2