Quarter	Percent
1998-01-01	55.3
1998-04-01	56.1
1998-07-01	56.5
1998-10-01	56
1999-01-01	56
1999-04-01	56
1999-07-01	56.1
1999-10-01	55.5
2000-01-01	55.7
2000-04-01	56.6
2000-07-01	56.9
2000-10-01	56.6
2001-01-01	56.1
2001-04-01	56.5
2001-07-01	56.8
2001-10-01	55.9
2002-01-01	56.1
2002-04-01	57.6
2002-07-01	58
2002-10-01	57.8
2003-01-01	57.9
2003-04-01	58.7
2003-07-01	58.9
2003-10-01	58.5
2004-01-01	58.4
2004-04-01	59.3
2004-07-01	59.4
2004-10-01	59.2
2005-01-01	59.1
2005-04-01	59.8
2005-07-01	59.8
2005-10-01	59.8
2006-01-01	60
2006-04-01	60.6
2006-07-01	61.1
2006-10-01	60.5
2007-01-01	60.2
2007-04-01	61
2007-07-01	61.3
2007-10-01	61
2008-01-01	60.8
2008-04-01	61.8
2008-07-01	61.8
2008-10-01	61.3
2009-01-01	60.6
2009-04-01	61.2
2009-07-01	61.3
2009-10-01	60.3
2010-01-01	59.6
2010-04-01	59.7
2010-07-01	59.3
2010-10-01	57.8
2011-01-01	56.4
2011-04-01	56
2011-07-01	55
2011-10-01	53
2012-01-01	51.8
2012-04-01	51.2
2012-07-01	50.5
2012-10-01	49.7
2013-01-01	48.6
2013-04-01	49.1
2013-07-01	49.1
2013-10-01	48.4
2014-01-01	48.5
2014-04-01	49.4
2014-07-01	50.2
2014-10-01	49.6
2015-01-01	49.2
2015-04-01	51.0
2015-07-01	51.7
2015-10-01	51.3
2016-01-01	50.9
2016-04-01	52.4
2016-07-01	53.0
2016-10-01	51.8
2017-01-01	52.0
2017-04-01	54.0
2017-07-01	54.6
2017-10-01	53.4
2018-01-01	53.3
2018-04-01	55.3