Quarter	Percent
1998-01-01	58.7
1998-04-01	59.8
1998-07-01	57.0
1998-10-01	56.6
1999-01-01	58.2
1999-04-01	59.1
1999-07-01	57.2
1999-10-01	57.3
2000-01-01	59.1
2000-04-01	59.8
2000-07-01	59.5
2000-10-01	59.3
2001-01-01	60.5
2001-04-01	62.4
2001-07-01	62.5
2001-10-01	62.9
2002-01-01	65.3
2002-04-01	65.7
2002-07-01	64.1
2002-10-01	63.9
2003-01-01	65.7
2003-04-01	67.2
2003-07-01	65.5
2003-10-01	65.7
2004-01-01	67.9
2004-04-01	68.7
2004-07-01	68.7
2004-10-01	68.6
2005-01-01	71.6
2005-04-01	72.4
2005-07-01	71.1
2005-10-01	69.3
2006-01-01	71.5
2006-04-01	71.5
2006-07-01	70
2006-10-01	70.4
2007-01-01	72.7
2007-04-01	73.5
2007-07-01	73
2007-10-01	73.3
2008-01-01	75
2008-04-01	74.6
2008-07-01	73.1
2008-10-01	72.9
2009-01-01	74.4
2009-04-01	74.8
2009-07-01	73
2009-10-01	73.4
2010-01-01	76
2010-04-01	76
2010-07-01	73
2010-10-01	73.9
2011-01-01	76.1
2011-04-01	76.3
2011-07-01	74.7
2011-10-01	76.5
2012-01-01	75
2012-04-01	74.9
2012-07-01	73.2
2012-10-01	73.1
2013-01-01	74.3
2013-04-01	74.3
2013-07-01	73.3
2013-10-01	73.8
2014-01-01	75.6
2014-04-01	75.3
2014-07-01	72.9
2014-10-01	71.9
2015-01-01	72.7
2015-04-01	73.1
2015-07-01	71.7
2015-10-01	73.1
2016-01-01	74.8
2016-04-01	74.9
2016-07-01	72.7
2016-10-01	72.7
2017-01-01	73.2
2017-04-01	74.5
2017-07-01	72.4
2017-10-01	73.6
2018-01-01	74.9
2018-04-01	74.3