Quarter	Percent
1999-04-01	53.2
1999-07-01	41.6
1999-10-01	50.7
2000-01-01	52.7
2000-04-01	53.3
2000-07-01	42.5
2000-10-01	51.2
2001-01-01	53.2
2001-04-01	55.2
2001-07-01	44.1
2001-10-01	52.4
2002-01-01	53.3
2002-04-01	55.4
2002-07-01	45.8
2002-10-01	52.9
2003-01-01	54.4
2003-04-01	54.5
2003-07-01	45.4
2003-10-01	51.9
2004-01-01	53.4
2004-04-01	55.3
2004-07-01	45.8
2004-10-01	50.2
2005-01-01	52.7
2005-04-01	52.4
2005-07-01	44.8
2005-10-01	50.6
2006-01-01	52.4
2006-04-01	51.8
2006-07-01	43.4
2006-10-01	50.1
2007-01-01	38.9
2007-04-01	35.6
2007-07-01	31.7
2007-10-01	37.1
2008-01-01	39.6
2008-04-01	37.3
2008-07-01	34.1
2008-10-01	41.6
2009-01-01	43.1
2009-04-01	40.6
2009-07-01	41.2
2009-10-01	45.6
2010-01-01	51.1
2010-04-01	47.5
2010-07-01	46.5
2010-10-01	48.0
2011-01-01	51.7
2011-04-01	49.7
2011-07-01	50.0
2011-10-01	52.1
2012-01-01	53.2
2012-04-01	50.0
2012-07-01	48.9
2012-10-01	53.3
2013-01-01	55.0
2013-04-01	49.9
2013-07-01	48.5
2013-10-01	54.1
2014-01-01	57.2
2014-04-01	55.0
2014-07-01	49.9
2014-10-01	54.6
2015-01-01	58.1
2015-04-01	56.0
2015-07-01	51.8
2015-10-01	55.8
2016-01-01	58.1
2016-04-01	49.0
2016-07-01	47.8
2016-10-01	51.5
2017-01-01	54.8
2017-04-01	51.9
2017-07-01	54.8
2017-10-01	56.5
2018-01-01	59.3
2018-04-01	54.2