Quarter	Percent
1998-01-01	29.9
1999-01-01	30.7
1999-04-01	29.8
1999-07-01	28.8
1999-10-01	27
2000-01-01	31.4
2000-04-01	30.7
2000-07-01	29.4
2000-10-01	30.4
2001-01-01	29
2001-04-01	30.9
2001-07-01	29.8
2001-10-01	30.9
2002-01-01	29.7
2002-04-01	30.8
2002-07-01	31
2002-10-01	31.5
2003-01-01	31
2003-04-01	32.7
2003-07-01	32
2003-10-01	32.3
2004-01-01	27.2
2004-04-01	28.6
2004-07-01	28.3
2004-10-01	29.2
2005-01-01	29.7
2005-04-01	31
2005-07-01	31.7
2005-10-01	32.2
2006-01-01	33.5
2006-04-01	34.4
2006-07-01	34.4
2006-10-01	35.1
2007-01-01	35.8
2007-04-01	37.7
2007-07-01	37.8
2007-10-01	37.7
2008-01-01	39.7
2008-04-01	39.9
2008-07-01	39.7
2008-10-01	39.6
2009-01-01	39.3
2009-04-01	40.4
2009-07-01	41
2009-10-01	41.4
2010-01-01	41.9
2010-04-01	42.4
2010-07-01	43.1
2010-10-01	41.5
2011-01-01	41.2
2011-04-01	41.8
2011-07-01	41.7
2011-10-01	41.1
2012-01-01	41.1
2012-04-01	43.3
2012-07-01	43.9
2012-10-01	44.1
2013-01-01	43.9
2013-04-01	46
2013-07-01	45.9
2013-10-01	46.2
2014-01-01	45.3
2014-04-01	47.4
2014-07-01	47.2
2014-10-01	47.7
2015-01-01	47.4
2015-04-01	48.2
2015-07-01	48.9
2015-10-01	49.7
2016-01-01	50.4
2016-04-01	52.2
2016-07-01	52.1
2016-10-01	52.2
2017-01-01	52.3
2017-04-01	53.2
2017-07-01	53.9
2017-10-01	54.8
2018-01-01	55.4
2018-04-01	55.6