Quarter	Percent
1999-04-01	46.8
1999-07-01	49.2
1999-10-01	48.1
2000-01-01	48.1
2000-04-01	48.8
2000-07-01	51
2000-10-01	49.7
2001-01-01	49.5
2001-04-01	49.6
2001-07-01	51.8
2001-10-01	50.6
2002-01-01	50.6
2002-04-01	50.7
2002-07-01	51.8
2002-10-01	50.5
2003-01-01	50.6
2003-04-01	50.9
2003-07-01	52.1
2003-10-01	51.4
2004-01-01	51.3
2004-04-01	51.3
2004-07-01	52.7
2004-10-01	52.7
2005-01-01	53
2005-04-01	53.4
2005-07-01	54.6
2005-10-01	53.9
2006-01-01	54
2006-04-01	54.4
2006-07-01	55.6
2006-10-01	55.1
2007-01-01	57.6
2007-04-01	58.2
2007-07-01	59.0
2007-10-01	58.4
2008-01-01	58.1
2008-04-01	58.0
2008-07-01	57.8
2008-10-01	56.7
2009-01-01	55.2
2009-04-01	55.0
2009-07-01	54.6
2009-10-01	53.8
2010-01-01	53.1
2010-04-01	53.1
2010-07-01	52.6
2010-10-01	52.1
2011-01-01	51.7
2011-04-01	52.4
2011-07-01	51.6
2011-10-01	51.9
2012-01-01	51.4
2012-04-01	51.7
2012-07-01	51.5
2012-10-01	51.8
2013-01-01	51.5
2013-04-01	52.3
2013-07-01	52.9
2013-10-01	52.7
2014-01-01	52.2
2014-04-01	52.6
2014-07-01	53.4
2014-10-01	53.8
2015-01-01	53.2
2015-04-01	53.9
2015-07-01	54.4
2015-10-01	55.0
2016-01-01	54.8
2016-04-01	55.8
2016-07-01	56.1
2016-10-01	56.1
2017-01-01	55.9
2017-04-01	56.5
2017-07-01	56.6
2017-10-01	57.3
2018-01-01	56.6
2018-04-01	57.6