Quarter	Percent
1998-01-01	31.9
1998-04-01	29.3
1998-07-01	30.1
1998-10-01	30.8
1999-01-01	31.9
1999-04-01	31.4
1999-07-01	30.9
1999-10-01	32.2
2000-01-01	30.9
2000-04-01	29.2
2000-07-01	28.7
2000-10-01	28
2001-01-01	29
2001-04-01	27.9
2001-07-01	26.9
2001-10-01	28.4
2002-01-01	28.6
2002-04-01	25.8
2002-07-01	25.6
2002-10-01	26.2
2003-01-01	26.7
2003-04-01	25.4
2003-07-01	26.6
2003-10-01	27.9
2004-01-01	28.4
2004-04-01	26.1
2004-07-01	25.2
2004-10-01	26.3
2005-01-01	25.4
2005-04-01	25
2005-07-01	26
2005-10-01	26.7
2006-01-01	25.1
2006-04-01	24.3
2006-07-01	24.2
2006-10-01	26.3
2007-01-01	24.8
2007-04-01	21.7
2007-07-01	21.9
2007-10-01	22.3
2008-01-01	23.2
2008-04-01	20.4
2008-07-01	21.1
2008-10-01	22.8
2009-01-01	25.3
2009-04-01	24.5
2009-07-01	24.7
2009-10-01	28.4
2010-01-01	30.6
2010-04-01	31.4
2010-07-01	32.8
2010-10-01	37.2
2011-01-01	39.9
2011-04-01	43.3
2011-07-01	45.4
2011-10-01	50.2
2012-01-01	52.8
2012-04-01	53.9
2012-07-01	56.6
2012-10-01	57.9
2013-01-01	60
2013-04-01	59.2
2013-07-01	57.1
2013-10-01	56.7
2014-01-01	56.7
2014-04-01	52
2014-07-01	49.5
2014-10-01	51.5
2015-01-01	51.9
2015-04-01	49.5
2015-07-01	48.8
2015-10-01	49.0
2016-01-01	50.9
2016-04-01	49.1
2016-07-01	44.2
2016-10-01	45.2
2017-01-01	46.8
2017-04-01	43.8
2017-07-01	40.1
2017-10-01	43.6
2018-01-01	44.4
2018-04-01	38.8