Quarter	Percent
1998-01-01	38.6
1998-04-01	37.1
1998-07-01	39.9
1998-10-01	39.9
1999-01-01	41.4
1999-04-01	42.2
1999-07-01	42.3
1999-10-01	41.4
2000-01-01	42.5
2000-04-01	44.6
2000-07-01	44.7
2000-10-01	46.2
2001-01-01	46.6
2001-04-01	49.4
2001-07-01	50.9
2001-10-01	50.4
2002-01-01	50.1
2002-04-01	50.7
2002-07-01	52.5
2002-10-01	51.6
2003-01-01	52.3
2003-04-01	52.7
2003-07-01	52.2
2003-10-01	51.7
2004-01-01	53.4
2004-04-01	54.4
2004-07-01	54.5
2004-10-01	54.8
2005-01-01	55.5
2005-04-01	56.1
2005-07-01	57.2
2005-10-01	56.7
2006-01-01	57.4
2006-04-01	57.2
2006-07-01	58.3
2006-10-01	59.8
2007-01-01	59.3
2007-04-01	58.5
2007-07-01	58
2007-10-01	57.9
2008-01-01	58
2008-04-01	58.5
2008-07-01	59.3
2008-10-01	59.4
2009-01-01	59.4
2009-04-01	59.1
2009-07-01	60.4
2009-10-01	59.4
2010-01-01	59.5
2010-04-01	60.7
2010-07-01	60.5
2010-10-01	60.5
2011-01-01	60
2011-04-01	61.1
2011-07-01	60.3
2011-10-01	60.2
2012-01-01	62.6
2012-04-01	62.4
2012-07-01	64.3
2012-10-01	62.4
2013-01-01	63.7
2013-04-01	64
2013-07-01	64.8
2013-10-01	64.6
2014-01-01	65.1
2014-04-01	66.4
2014-07-01	65
2014-10-01	65.7
2015-01-01	66.2
2015-04-01	67.5
2015-07-01	67.9
2015-10-01	67.1
2016-01-01	68.1
2016-04-01	67.0
2016-07-01	67.4
2016-10-01	68.1
2017-01-01	68.6
2017-04-01	68.2
2017-07-01	67.1
2017-10-01	68.7
2018-01-01	72.5
2018-04-01	70.2