Quarter	Percent
1998-01-01	55.1
1998-04-01	55.4
1998-07-01	54.8
1998-10-01	55.1
1999-01-01	55.7
1999-04-01	55.9
1999-07-01	56.5
1999-10-01	56.6
2000-01-01	55.4
2000-04-01	54.5
2000-07-01	54.6
2000-10-01	53.5
2001-01-01	54.1
2001-04-01	54.7
2001-07-01	54.8
2001-10-01	56.3
2002-01-01	57.8
2002-04-01	58.3
2002-07-01	60.2
2002-10-01	60.7
2003-01-01	60.3
2003-04-01	59.5
2003-07-01	60.3
2003-10-01	59.6
2004-01-01	59.8
2004-04-01	59.7
2004-07-01	60.5
2004-10-01	60.7
2005-01-01	61.7
2005-04-01	61.9
2005-07-01	63.1
2005-10-01	61.9
2006-01-01	63.5
2006-04-01	62.7
2006-07-01	62.8
2006-10-01	62
2007-01-01	61.8
2007-04-01	61.8
2007-07-01	63.3
2007-10-01	63
2008-01-01	63.5
2008-04-01	64.3
2008-07-01	64.2
2008-10-01	64.6
2009-01-01	64.1
2009-04-01	63.7
2009-07-01	62.9
2009-10-01	61.9
2010-01-01	62.2
2010-04-01	62.3
2010-07-01	62.8
2010-10-01	62.5
2011-01-01	62.5
2011-04-01	63.8
2011-07-01	62.7
2011-10-01	61.4
2012-01-01	61.9
2012-04-01	63.7
2012-07-01	65.3
2012-10-01	65.2
2013-01-01	65.3
2013-04-01	66
2013-07-01	66.5
2013-10-01	66.5
2014-01-01	66.8
2014-04-01	67.2
2014-07-01	68.7
2014-10-01	69
2015-01-01	67.7
2015-04-01	68.4
2015-07-01	68.4
2015-10-01	68.6
2016-01-01	69.6
2016-04-01	70.6
2016-07-01	71.4
2016-10-01	72.2
2017-01-01	71.9
2017-04-01	73.2
2017-07-01	73.4
2017-10-01	74.2
2018-01-01	74.8
2018-04-01	75.4