Quarter	Percent
1999-01-01	30.9
2000-01-01	31.7
2001-01-01	32.6
2002-01-01	35.6
2003-01-01	38.2
2003-04-01	38.9
2003-07-01	38.5
2003-10-01	39.2
2004-01-01	39.7
2004-04-01	39.7
2004-07-01	39.7
2004-10-01	39.9
2005-01-01	40.6
2005-04-01	41.0
2005-07-01	40.0
2005-10-01	39.9
2006-01-01	40.3
2006-04-01	40.5
2006-07-01	39.7
2006-10-01	39.8
2007-01-01	40.2
2007-04-01	40.7
2007-07-01	39.5
2007-10-01	39.5
2008-01-01	39.2
2008-04-01	39.9
2008-07-01	39.6
2008-10-01	40.3
2009-01-01	40.7
2009-04-01	41.8
2009-07-01	40.8
2009-10-01	41.4
2010-01-01	41.5
2010-04-01	42.3
2010-07-01	42.4
2010-10-01	42.4
2011-01-01	42.6
2011-04-01	43.8
2011-07-01	43.9
2011-10-01	45.2
2012-01-01	45.9
2012-04-01	47.1
2012-07-01	47.6
2012-10-01	49.0
2013-01-01	48.7
2013-04-01	49
2013-07-01	49.2
2013-10-01	49.3
2014-01-01	50.0
2014-04-01	50.6
2014-07-01	50.6
2014-10-01	51.6
2015-01-01	51.8
2015-04-01	53.1
2015-07-01	52.7
2015-10-01	52.7
2016-01-01	53.2
2016-04-01	53.5
2016-07-01	53.9
2016-10-01	54.0
2017-01-01	54.3
2017-04-01	55.1
2017-07-01	54.5
2017-10-01	55.5
2018-01-01	55.8
2018-04-01	55.9