Quarter	Percent
1999-04-01	21.9
2000-01-01	24.8
2000-04-01	25.8
2000-07-01	26.4
2000-10-01	27.4
2001-01-01	27.8
2001-04-01	28
2001-07-01	28
2001-10-01	28.2
2002-01-01	29.1
2002-04-01	29
2002-07-01	31.1
2002-10-01	30.5
2003-01-01	31.4
2003-04-01	32
2003-07-01	32
2003-10-01	31.8
2004-01-01	32.6
2004-04-01	32.5
2004-07-01	34.1
2004-10-01	34.4
2005-01-01	34.7
2005-04-01	35
2005-07-01	35.3
2005-10-01	35.7
2006-01-01	36.2
2006-04-01	36.7
2006-07-01	37.7
2006-10-01	38.3
2007-01-01	38.6
2007-04-01	40.2
2007-07-01	40.6
2007-10-01	40.7
2008-01-01	41.1
2008-04-01	42.1
2008-07-01	42.5
2008-10-01	43.1
2009-01-01	44.4
2009-04-01	44.1
2009-07-01	45.1
2009-10-01	45.1
2010-01-01	42.1
2010-04-01	42.4
2010-07-01	42.9
2010-10-01	43.9
2011-01-01	44.6
2011-04-01	45.3
2011-07-01	46.3
2011-10-01	47.3
2012-01-01	47.2
2012-04-01	48.0
2012-07-01	48.7
2012-10-01	49.4
2013-01-01	49.1
2013-04-01	49.5
2013-07-01	49.7
2013-10-01	49.8
2014-01-01	49.7
2014-04-01	49.9
2014-07-01	50.9
2014-10-01	51.1
2015-01-01	51.5
2015-04-01	52.4
2015-07-01	52.9
2015-10-01	52.8
2016-01-01	53.3
2016-04-01	54.4
2016-07-01	54.8
2016-10-01	54.4
2017-01-01	55.5
2017-04-01	56.4
2017-07-01	57.1
2017-10-01	57.5
2018-01-01	57.6
2018-04-01	58.5