Quarter	Percent
1998-01-01	28.8
1998-04-01	29
1998-07-01	29.3
1998-10-01	29.1
1999-01-01	28.6
1999-04-01	28.9
1999-07-01	29.4
1999-10-01	29.2
2000-01-01	28.2
2000-04-01	28.6
2000-07-01	29.4
2000-10-01	29.5
2001-01-01	28.8
2001-04-01	28.2
2001-07-01	29.6
2001-10-01	30.2
2002-01-01	29.5
2002-04-01	29.9
2002-07-01	30.5
2002-10-01	30.7
2003-01-01	30.4
2003-04-01	31.3
2003-07-01	31.8
2003-10-01	32.3
2004-01-01	30.5
2004-04-01	31.5
2004-07-01	32.4
2004-10-01	33.1
2005-01-01	32.2
2005-04-01	32.3
2005-07-01	32.4
2005-10-01	33.4
2006-01-01	32.5
2006-04-01	33.4
2006-07-01	33.9
2006-10-01	33.8
2007-01-01	33.8
2007-04-01	34.7
2007-07-01	35
2007-10-01	34.5
2008-01-01	34.2
2008-04-01	35.8
2008-07-01	35.9
2008-10-01	35.8
2009-01-01	36.2
2009-04-01	37.5
2009-07-01	36.8
2009-10-01	37.1
2010-01-01	37.6
2010-04-01	37.8
2010-07-01	37.7
2010-10-01	38.4
2011-01-01	38.8
2011-04-01	38.7
2011-07-01	39.2
2011-10-01	40.7
2012-01-01	41.2
2012-04-01	42.6
2012-07-01	42.8
2012-10-01	43.5
2013-01-01	43.7
2013-04-01	44.5
2013-07-01	45.8
2013-10-01	47
2014-01-01	47.6
2014-04-01	48.5
2014-07-01	49.5
2014-10-01	50.1
2015-01-01	50.4
2015-04-01	51.4
2015-07-01	51.1
2015-10-01	51.3
2016-01-01	52.4
2016-04-01	53.7
2016-07-01	53.4
2016-10-01	54.1
2017-01-01	54.5
2017-04-01	55.4
2017-07-01	55.5
2017-10-01	56.3
2018-01-01	56.4
2018-04-01	57.4