Quarter	Percent
1998-01-01	36
1998-04-01	35.7
1998-07-01	36.6
1998-10-01	36.8
1999-01-01	38.2
1999-04-01	39.2
1999-07-01	38.8
1999-10-01	39
2000-01-01	39.9
2000-04-01	41.2
2000-07-01	42.2
2000-10-01	43.4
2001-01-01	43.6
2001-04-01	45.5
2001-07-01	46.9
2001-10-01	46.9
2002-01-01	46.2
2002-04-01	47.8
2002-07-01	48.8
2002-10-01	48.6
2003-01-01	48.3
2003-04-01	49.6
2003-07-01	51
2003-10-01	49.6
2004-01-01	50.4
2004-04-01	51.1
2004-07-01	51.3
2004-10-01	51
2005-01-01	51.1
2005-04-01	52.7
2005-07-01	53.7
2005-10-01	53.4
2006-01-01	53.4
2006-04-01	54.2
2006-07-01	54.9
2006-10-01	55.7
2007-01-01	55
2007-04-01	55.4
2007-07-01	55.1
2007-10-01	54.7
2008-01-01	55.4
2008-04-01	56.8
2008-07-01	57
2008-10-01	56.6
2009-01-01	55.6
2009-04-01	55.8
2009-07-01	55.8
2009-10-01	54.6
2010-01-01	55.1
2010-04-01	56.7
2010-07-01	56.6
2010-10-01	56.6
2011-01-01	55.9
2011-04-01	57.5
2011-07-01	57.2
2011-10-01	57.2
2012-01-01	57.5
2012-04-01	58.3
2012-07-01	58.7
2012-10-01	58.2
2013-01-01	57.6
2013-04-01	59
2013-07-01	59.2
2013-10-01	58.4
2014-01-01	58.7
2014-04-01	59.4
2014-07-01	58.9
2014-10-01	59.5
2015-01-01	59.2
2015-04-01	59.5
2015-07-01	60.8
2015-10-01	60.4
2016-01-01	60.5
2016-04-01	61.2
2016-07-01	62.4
2016-10-01	61.5
2017-01-01	61.7
2017-04-01	62.4
2017-07-01	62.4
2017-10-01	63.7
2018-01-01	65.2
2018-04-01	65.1