Quarter	Percent
1999-01-01	64.6
1999-04-01	65.1
1999-07-01	65.1
1999-10-01	65.1
2000-01-01	65.9
2000-04-01	67.5
2000-07-01	66.7
2000-10-01	66.6
2001-01-01	69.4
2001-04-01	70.9
2001-07-01	69.7
2001-10-01	70.5
2002-01-01	71.1
2002-04-01	71.5
2002-07-01	70.2
2002-10-01	70
2003-01-01	71.2
2003-04-01	73.4
2003-07-01	72.7
2003-10-01	73.5
2004-01-01	74.6
2004-04-01	76.4
2004-07-01	76
2004-10-01	75.6
2005-01-01	75.9
2005-04-01	76.9
2005-07-01	75.9
2005-10-01	76.2
2006-01-01	77
2006-04-01	77.9
2006-07-01	75.6
2006-10-01	76.9
2007-01-01	78.2
2007-04-01	79.4
2007-07-01	77.1
2007-10-01	78.1
2008-01-01	79.3
2008-04-01	79.9
2008-07-01	77.6
2008-10-01	77.3
2009-01-01	79.6
2009-04-01	79.1
2009-07-01	77.6
2009-10-01	77.8
2010-01-01	78.4
2010-04-01	78.7
2010-07-01	77.5
2010-10-01	77.5
2011-01-01	79.1
2011-04-01	79.4
2011-07-01	77.7
2011-10-01	78.1
2012-01-01	78
2012-04-01	77.7
2012-07-01	75.2
2012-10-01	75.6
2013-01-01	76.6
2013-04-01	76.9
2013-07-01	75.5
2013-10-01	76.4
2014-01-01	75.6
2014-04-01	74.5
2014-07-01	73.2
2014-10-01	73.2
2015-01-01	73.7
2015-04-01	72.9
2015-07-01	71.5
2015-10-01	71.9
2016-01-01	72.8
2016-04-01	73.3
2016-07-01	70.5
2016-10-01	70.5
2017-01-01	72.0
2017-04-01	71.9
2017-07-01	71.5
2017-10-01	71.8
2018-01-01	74.3
2018-04-01	73.4