Quarter	Percent
1998-01-01	28
1999-01-01	29.2
1999-04-01	28.4
1999-07-01	27.4
1999-10-01	25.6
2000-01-01	29.2
2000-04-01	29.3
2000-07-01	28.1
2000-10-01	28.8
2001-01-01	27.4
2001-04-01	29.4
2001-07-01	28.4
2001-10-01	29.5
2002-01-01	28
2002-04-01	29.1
2002-07-01	29.4
2002-10-01	29.8
2003-01-01	29.1
2003-04-01	31
2003-07-01	30.4
2003-10-01	30.6
2004-01-01	25.9
2004-04-01	27.5
2004-07-01	27.2
2004-10-01	28
2005-01-01	28.5
2005-04-01	29.9
2005-07-01	30.5
2005-10-01	30.9
2006-01-01	32.1
2006-04-01	32.9
2006-07-01	33.2
2006-10-01	33.7
2007-01-01	34.4
2007-04-01	35.9
2007-07-01	36.8
2007-10-01	36.7
2008-01-01	38.8
2008-04-01	38.8
2008-07-01	39
2008-10-01	38.6
2009-01-01	38.3
2009-04-01	39.3
2009-07-01	39.7
2009-10-01	40.4
2010-01-01	40.8
2010-04-01	41.4
2010-07-01	42
2010-10-01	40.5
2011-01-01	39.6
2011-04-01	40.3
2011-07-01	40.4
2011-10-01	39.4
2012-01-01	39.7
2012-04-01	41.8
2012-07-01	42.3
2012-10-01	42.6
2013-01-01	42.1
2013-04-01	44.4
2013-07-01	44.1
2013-10-01	44.4
2014-01-01	43.5
2014-04-01	45.7
2014-07-01	45.5
2014-10-01	45.7
2015-01-01	45.1
2015-04-01	46.1
2015-07-01	46.7
2015-10-01	47.2
2016-01-01	47.9
2016-04-01	49.5
2016-07-01	49.7
2016-10-01	49.6
2017-01-01	49.7
2017-04-01	50.8
2017-07-01	51.8
2017-10-01	52.8
2018-01-01	53.4
2018-04-01	53.4