Quarter	Percent
1998-01-01	53.1
1998-04-01	53.4
1998-07-01	52.9
1998-10-01	53.2
1999-01-01	53.4
1999-04-01	53.2
1999-07-01	54
1999-10-01	53.8
2000-01-01	52.2
2000-04-01	51.6
2000-07-01	52.1
2000-10-01	51.1
2001-01-01	51.5
2001-04-01	52.4
2001-07-01	52.5
2001-10-01	53.9
2002-01-01	55.3
2002-04-01	56.2
2002-07-01	58.3
2002-10-01	58.7
2003-01-01	58.1
2003-04-01	57.3
2003-07-01	57.8
2003-10-01	56.9
2004-01-01	56.6
2004-04-01	56.7
2004-07-01	57.6
2004-10-01	57.8
2005-01-01	58.9
2005-04-01	59.1
2005-07-01	60.3
2005-10-01	59.1
2006-01-01	60.2
2006-04-01	59.5
2006-07-01	59.6
2006-10-01	58.7
2007-01-01	58.9
2007-04-01	58.7
2007-07-01	60.5
2007-10-01	60.4
2008-01-01	61.1
2008-04-01	61.9
2008-07-01	62.3
2008-10-01	62.4
2009-01-01	61.1
2009-04-01	60.5
2009-07-01	58.9
2009-10-01	58.1
2010-01-01	57.6
2010-04-01	58.4
2010-07-01	59
2010-10-01	58.7
2011-01-01	58.5
2011-04-01	59.8
2011-07-01	59.1
2011-10-01	58.3
2012-01-01	58.1
2012-04-01	60
2012-07-01	62
2012-10-01	61.3
2013-01-01	61.1
2013-04-01	62.4
2013-07-01	63.2
2013-10-01	63.3
2014-01-01	62.9
2014-04-01	64.6
2014-07-01	65.6
2014-10-01	66.1
2015-01-01	64.7
2015-04-01	65.7
2015-07-01	65.9
2015-10-01	65.8
2016-01-01	66.1
2016-04-01	67.9
2016-07-01	68.8
2016-10-01	70.0
2017-01-01	70.0
2017-04-01	71.6
2017-07-01	72.0
2017-10-01	73.0
2018-01-01	73.5
2018-04-01	74.0