Quarter	Percent
1999-01-01	38.8
1999-04-01	38.7
1999-07-01	38.8
1999-10-01	38.9
2000-01-01	39.7
2000-04-01	40.8
2000-07-01	41.2
2000-10-01	41.8
2001-01-01	41.5
2001-04-01	41.7
2001-07-01	42
2001-10-01	42.4
2002-01-01	42.5
2002-04-01	43
2002-07-01	43
2002-10-01	43.6
2003-01-01	43.6
2003-04-01	43.9
2003-07-01	44.1
2003-10-01	44.4
2004-01-01	44.4
2004-04-01	44.3
2004-07-01	44.4
2004-10-01	44.7
2005-01-01	45.5
2005-04-01	46.2
2005-07-01	45.5
2005-10-01	46.7
2006-01-01	47.2
2006-04-01	46.9
2006-07-01	46.3
2006-10-01	46.9
2007-01-01	46.9
2007-04-01	47.4
2007-07-01	47.2
2007-10-01	47.8
2008-01-01	48.5
2008-04-01	49.1
2008-07-01	49
2008-10-01	49.8
2009-01-01	50
2009-04-01	50.6
2009-07-01	49.6
2009-10-01	49.9
2010-01-01	50.2
2010-04-01	50.5
2010-07-01	51
2010-10-01	51.3
2011-01-01	51.6
2011-04-01	52.4
2011-07-01	52.6
2011-10-01	53
2012-01-01	52.8
2012-04-01	53.8
2012-07-01	53.9
2012-10-01	53.5
2013-01-01	53.6
2013-04-01	53.8
2013-07-01	54.3
2013-10-01	54.5
2014-01-01	54.5
2014-04-01	55.2
2014-07-01	55.4
2014-10-01	56.5
2015-01-01	56.7
2015-04-01	57.4
2015-07-01	57.6
2015-10-01	58.8
2016-01-01	59.2
2016-04-01	58.9
2016-07-01	59.4
2016-10-01	59.3
2017-01-01	59.3
2017-04-01	59.7
2017-07-01	59.6
2017-10-01	59.9
2018-01-01	60.1
2018-04-01	60.5
2018-07-01	60.3