Quarter	Percent
1999-01-01	52.9
1999-04-01	53.8
1999-07-01	54.3
1999-10-01	54.5
2000-01-01	53.6
2000-04-01	54.3
2000-07-01	55.1
2000-10-01	55.3
2001-01-01	53.9
2001-04-01	54.1
2001-07-01	54.5
2001-10-01	54.1
2002-01-01	53.6
2002-04-01	54.1
2002-07-01	54.5
2002-10-01	54.3
2003-01-01	53.5
2003-04-01	54.6
2003-07-01	55.1
2003-10-01	54.9
2004-01-01	54.1
2004-04-01	54.4
2004-07-01	54.6
2004-10-01	54.5
2005-01-01	53.7
2005-04-01	54.1
2005-07-01	54.7
2005-10-01	54.5
2006-01-01	53.9
2006-04-01	55
2006-07-01	55.1
2006-10-01	55.1
2007-01-01	54.2
2007-04-01	54.8
2007-07-01	55
2007-10-01	54.1
2008-01-01	53.2
2008-04-01	53.8
2008-07-01	54.4
2008-10-01	53.3
2009-01-01	51.6
2009-04-01	52.3
2009-07-01	52
2009-10-01	51.8
2010-01-01	50.1
2010-04-01	51
2010-07-01	51.8
2010-10-01	51.6
2011-01-01	50.5
2011-04-01	51.9
2011-07-01	52.7
2011-10-01	52.4
2012-01-01	51.2
2012-04-01	52.4
2012-07-01	53.3
2012-10-01	53.2
2013-01-01	51.6
2013-04-01	54.1
2013-07-01	55.1
2013-10-01	55.3
2014-01-01	56.2
2014-04-01	56.8
2014-07-01	58
2014-10-01	57.7
2015-01-01	57.3
2015-04-01	58.8
2015-07-01	59.8
2015-10-01	59.8
2016-01-01	59.8
2016-04-01	61.0
2016-07-01	61.6
2016-10-01	61.8
2017-01-01	61.5
2017-04-01	62.7
2017-07-01	63.3
2017-10-01	63.3
2018-01-01	63.0
2018-04-01	63.4