Quarter	Percent
1999-01-01	54.3
2000-01-01	58.9
2000-04-01	58.9
2000-07-01	59.4
2000-10-01	61.2
2001-01-01	61.7
2001-04-01	59.2
2001-07-01	59.8
2001-10-01	61.1
2002-01-01	61.6
2002-04-01	60.3
2002-07-01	61.1
2002-10-01	62
2003-01-01	61.7
2003-04-01	60.5
2003-07-01	59.5
2003-10-01	59.6
2004-01-01	61.7
2004-04-01	61.1
2004-07-01	60.8
2004-10-01	60.2
2005-01-01	61
2005-04-01	60.1
2005-07-01	57.6
2005-10-01	57.9
2006-01-01	59.4
2006-04-01	58.6
2006-07-01	56.2
2006-10-01	55.8
2007-01-01	56.7
2007-04-01	55.3
2007-07-01	54.9
2007-10-01	54.1
2008-01-01	53.9
2008-04-01	53.3
2008-07-01	53.1
2008-10-01	52.7
2009-01-01	53.2
2009-04-01	53.3
2009-07-01	51.2
2009-10-01	52.4
2010-01-01	52
2010-04-01	52
2010-07-01	50.5
2010-10-01	49.9
2011-01-01	49.6
2011-04-01	48.6
2011-07-01	47.6
2011-10-01	47.8
2012-01-01	48.1
2012-04-01	46.1
2012-07-01	45.8
2012-10-01	45.9
2013-01-01	45.3
2013-04-01	44.3
2013-07-01	43.5
2013-10-01	43.2
2014-01-01	44.2
2014-04-01	43.5
2014-07-01	42
2014-10-01	41.5
2015-01-01	43.1
2015-04-01	44.1
2015-07-01	41.7
2015-10-01	40.9
2016-01-01	41.8
2016-04-01	42.6
2016-07-01	41.4
2016-10-01	39.6
2017-01-01	40.1
2017-04-01	39.9
2017-07-01	38.6
2017-10-01	38.2
2018-01-01	39.8
2018-04-01	38.6