Quarter	Percent
1998-01-01	27.4
1998-04-01	27.7
1998-07-01	28
1998-10-01	27.7
1999-01-01	27.2
1999-04-01	27.5
1999-07-01	28
1999-10-01	27.8
2000-01-01	26.9
2000-04-01	27.3
2000-07-01	28.2
2000-10-01	28.3
2001-01-01	27.6
2001-04-01	26.9
2001-07-01	28.3
2001-10-01	29
2002-01-01	28.3
2002-04-01	28.6
2002-07-01	29.2
2002-10-01	29.5
2003-01-01	29.1
2003-04-01	30
2003-07-01	30.6
2003-10-01	31.2
2004-01-01	29.1
2004-04-01	30.2
2004-07-01	31.1
2004-10-01	31.8
2005-01-01	30.9
2005-04-01	31.1
2005-07-01	31.4
2005-10-01	32.2
2006-01-01	31.3
2006-04-01	32.6
2006-07-01	33
2006-10-01	32.8
2007-01-01	32.9
2007-04-01	33.9
2007-07-01	34.2
2007-10-01	33.7
2008-01-01	33
2008-04-01	34.6
2008-07-01	34.8
2008-10-01	34.8
2009-01-01	34.8
2009-04-01	36.2
2009-07-01	35.6
2009-10-01	35.8
2010-01-01	36.1
2010-04-01	36.5
2010-07-01	36.5
2010-10-01	36.9
2011-01-01	37.3
2011-04-01	37.3
2011-07-01	37.9
2011-10-01	38.9
2012-01-01	39
2012-04-01	40.3
2012-07-01	40.8
2012-10-01	41.1
2013-01-01	40.9
2013-04-01	42.1
2013-07-01	43.5
2013-10-01	44.2
2014-01-01	44.9
2014-04-01	45.9
2014-07-01	46.9
2014-10-01	47.2
2015-01-01	47.5
2015-04-01	48.6
2015-07-01	48.5
2015-10-01	48.4
2016-01-01	49.2
2016-04-01	50.7
2016-07-01	50.5
2016-10-01	50.9
2017-01-01	51.1
2017-04-01	52.3
2017-07-01	52.4
2017-10-01	53.1
2018-01-01	53.0
2018-04-01	54.1