Quarter	Percent
1998-01-01	55.5
1999-01-01	54.2
1999-04-01	51.6
1999-07-01	56.5
1999-10-01	56.5
2000-01-01	51.5
2000-04-01	49.1
2000-07-01	51.8
2000-10-01	49.8
2001-01-01	50.1
2001-04-01	48.9
2001-07-01	50
2001-10-01	49.9
2002-01-01	51
2002-04-01	49.5
2002-07-01	51
2002-10-01	49.7
2003-01-01	49.7
2003-04-01	49.7
2003-07-01	51.1
2003-10-01	48.6
2004-01-01	51.2
2004-04-01	51.8
2004-07-01	55.7
2004-10-01	53.1
2005-01-01	53.5
2005-04-01	52.6
2005-07-01	56.6
2005-10-01	53.7
2006-01-01	52.7
2006-04-01	52.1
2006-07-01	57.1
2006-10-01	54.3
2007-01-01	55.3
2007-04-01	54.2
2007-07-01	59.4
2007-10-01	55.2
2008-01-01	55.3
2008-04-01	53.3
2008-07-01	58.4
2008-10-01	57.6
2009-01-01	55.5
2009-04-01	54.8
2009-07-01	60.1
2009-10-01	54.4
2010-01-01	52.8
2010-04-01	51.7
2010-07-01	57.4
2010-10-01	54
2011-01-01	54.9
2011-04-01	52.4
2011-07-01	57.6
2011-10-01	54.4
2012-01-01	54.1
2012-04-01	51.9
2012-07-01	59.4
2012-10-01	56.1
2013-01-01	53.5
2013-04-01	53.4
2013-07-01	59.1
2013-10-01	55.2
2014-01-01	54.5
2014-04-01	54.2
2014-07-01	57.1
2014-10-01	55.7
2015-01-01	52.7
2015-04-01	52.4
2015-07-01	57.9
2015-10-01	53.6
2016-01-01	53.5
2016-04-01	52.1
2016-07-01	58.9
2016-10-01	54.0
2017-01-01	53.0
2017-04-01	53.2
2017-07-01	56.0
2017-10-01	52.7
2018-01-01	51.7
2018-04-01	51.7