Quarter	Percent
1999-01-01	23.1
1999-04-01	22.2
1999-07-01	21.7
1999-10-01	22
2000-01-01	21.5
2000-04-01	21.5
2000-07-01	21
2000-10-01	21.4
2001-01-01	21.8
2001-04-01	22.4
2001-07-01	22.5
2001-10-01	22.7
2002-01-01	22.6
2002-04-01	22.1
2002-07-01	22.8
2002-10-01	23.8
2003-01-01	23.1
2003-04-01	24.6
2003-07-01	25.5
2003-10-01	25.4
2004-01-01	25.3
2004-04-01	26
2004-07-01	27.6
2004-10-01	28.1
2005-01-01	28.5
2005-04-01	29.7
2005-07-01	31.1
2005-10-01	31.8
2006-01-01	32.1
2006-04-01	32.6
2006-07-01	33.7
2006-10-01	33.8
2007-01-01	34.1
2007-04-01	35.1
2007-07-01	36.4
2007-10-01	36.9
2008-01-01	37.4
2008-04-01	38.3
2008-07-01	40.8
2008-10-01	40.4
2009-01-01	39.2
2009-04-01	39.7
2009-07-01	40.2
2009-10-01	38.9
2010-01-01	40.2
2010-04-01	41
2010-07-01	40.9
2010-10-01	40.1
2011-01-01	40.1
2011-04-01	41.3
2011-07-01	42.2
2011-10-01	41.8
2012-01-01	42.1
2012-04-01	43.3
2012-07-01	43
2012-10-01	43.8
2013-01-01	44.3
2013-04-01	44
2013-07-01	44.2
2013-10-01	43.7
2014-01-01	42.8
2014-04-01	44.3
2014-07-01	46
2014-10-01	46
2015-01-01	45.9
2015-04-01	46.7
2015-07-01	47.6
2015-10-01	47.7
2016-01-01	47.5
2016-04-01	48.8
2016-07-01	49.5
2016-10-01	50.4
2017-01-01	51.7
2017-04-01	52.7
2017-07-01	53.3
2017-10-01	54.1
2018-01-01	54.0
2018-04-01	53.4