Quarter	Percent
1998-01-01	48.7
1998-04-01	48.8
1998-07-01	49.4
1998-10-01	49.3
1999-01-01	50.5
1999-04-01	50.4
1999-07-01	50.2
1999-10-01	50.2
2000-01-01	50.2
2000-04-01	50.6
2000-07-01	50.8
2000-10-01	50.4
2001-01-01	50.3
2001-04-01	49.8
2001-07-01	49.8
2001-10-01	49.3
2002-01-01	50.3
2002-04-01	51.2
2002-07-01	51.7
2002-10-01	51.6
2003-01-01	51.7
2003-04-01	52.2
2003-07-01	52.6
2003-10-01	52.6
2004-01-01	53.8
2004-04-01	54.2
2004-07-01	54.3
2004-10-01	54.3
2005-01-01	54
2005-04-01	54.5
2005-07-01	54.6
2005-10-01	54.7
2006-01-01	54.8
2006-04-01	54.9
2006-07-01	55.3
2006-10-01	54.8
2007-01-01	54.8
2007-04-01	55
2007-07-01	54.9
2007-10-01	54.7
2008-01-01	54.6
2008-04-01	55.1
2008-07-01	55.1
2008-10-01	55.3
2009-01-01	55.9
2009-04-01	56.4
2009-07-01	56.9
2009-10-01	56.7
2010-01-01	57.1
2010-04-01	57.6
2010-07-01	57.7
2010-10-01	57.6
2011-01-01	57.4
2011-04-01	57.2
2011-07-01	57.3
2011-10-01	57.9
2012-01-01	58
2012-04-01	58.1
2012-07-01	58.5
2012-10-01	58.5
2013-01-01	58
2013-04-01	58.6
2013-07-01	58.5
2013-10-01	58.1
2014-01-01	58.7
2014-04-01	59
2014-07-01	59.2
2014-10-01	59.1
2015-01-01	59.3
2015-04-01	59.9
2015-07-01	60.3
2015-10-01	60.2
2016-01-01	60.2
2016-04-01	60.6
2016-07-01	60.9
2016-10-01	60.1
2017-01-01	60.1
2017-04-01	60.9
2017-07-01	60.3
2017-10-01	59.7
2018-01-01	59.4
2018-04-01	60.4