Quarter	Percent
1999-01-01	59.5
1999-04-01	60.2
1999-07-01	59.8
1999-10-01	60.2
2000-01-01	61.3
2000-04-01	62.2
2000-07-01	61.5
2000-10-01	61.7
2001-01-01	64
2001-04-01	65.9
2001-07-01	65.3
2001-10-01	66.3
2002-01-01	67.4
2002-04-01	67.7
2002-07-01	66.9
2002-10-01	67.5
2003-01-01	67.9
2003-04-01	69.4
2003-07-01	68.8
2003-10-01	70.1
2004-01-01	71.2
2004-04-01	72.7
2004-07-01	72.2
2004-10-01	72.1
2005-01-01	72.6
2005-04-01	73.5
2005-07-01	72.7
2005-10-01	72.9
2006-01-01	74
2006-04-01	74.3
2006-07-01	72.2
2006-10-01	72.7
2007-01-01	74.1
2007-04-01	75
2007-07-01	73.6
2007-10-01	74.4
2008-01-01	75.4
2008-04-01	75.8
2008-07-01	73.7
2008-10-01	74.6
2009-01-01	76.3
2009-04-01	75.7
2009-07-01	74.5
2009-10-01	74.8
2010-01-01	75.5
2010-04-01	75.7
2010-07-01	74.7
2010-10-01	74.8
2011-01-01	75.9
2011-04-01	76.3
2011-07-01	74.8
2011-10-01	75.8
2012-01-01	76.2
2012-04-01	75.5
2012-07-01	73
2012-10-01	72.6
2013-01-01	73.7
2013-04-01	73.6
2013-07-01	71.2
2013-10-01	71.8
2014-01-01	71.4
2014-04-01	70.9
2014-07-01	69.7
2014-10-01	69.9
2015-01-01	70.3
2015-04-01	69.3
2015-07-01	67.9
2015-10-01	68.3
2016-01-01	68.8
2016-04-01	68.4
2016-07-01	66.7
2016-10-01	66.9
2017-01-01	68.3
2017-04-01	67.6
2017-07-01	67.0
2017-10-01	67.3
2018-01-01	69.1
2018-04-01	68.2