Quarter	Percent
1999-04-01	54.3
2000-04-01	52.5
2001-04-01	52
2002-04-01	52.6
2003-04-01	54.5
2004-04-01	57.2
2005-01-01	60
2005-04-01	60.9
2005-07-01	61.8
2005-10-01	62.3
2006-01-01	62.2
2006-04-01	63.4
2006-07-01	64.1
2006-10-01	65
2007-01-01	64.7
2007-04-01	66.2
2007-07-01	65.9
2007-10-01	66.4
2008-01-01	66.1
2008-04-01	67.7
2008-07-01	67.2
2008-10-01	67.8
2009-01-01	68.2
2009-04-01	69.6
2009-07-01	68.8
2009-10-01	70.4
2010-01-01	71.1
2010-04-01	70.9
2010-07-01	70.2
2010-10-01	71.1
2011-01-01	71.1
2011-04-01	72.1
2011-07-01	71.5
2011-10-01	72.5
2012-01-01	72.3
2012-04-01	72.5
2012-07-01	73.6
2012-10-01	73.9
2013-01-01	73.4
2013-04-01	74.1
2013-07-01	74.8
2013-10-01	75.6
2014-01-01	75.6
2014-04-01	75
2014-07-01	75.5
2014-10-01	75.9
2015-01-01	74.8
2015-04-01	74.5
2015-07-01	75.6
2015-10-01	76.1
2016-01-01	76.3
2016-04-01	76.6
2016-07-01	76.9
2016-10-01	77.7
2017-01-01	76.3
2017-04-01	77.9
2017-07-01	78.4
2017-10-01	78.9
2018-01-01	77.9
2018-04-01	78.1