Quarter	Percent
1999-01-01	31.8
1999-04-01	29.1
1999-07-01	28.3
1999-10-01	28.3
2000-01-01	27.8
2000-04-01	25.3
2000-07-01	25.3
2000-10-01	25.6
2001-01-01	21.6
2001-04-01	20.7
2001-07-01	20.7
2001-10-01	21.3
2002-01-01	22.1
2002-04-01	21.5
2002-07-01	22
2002-10-01	23.2
2003-01-01	23.4
2003-04-01	22.3
2003-07-01	22.2
2003-10-01	22.9
2004-01-01	22.6
2004-04-01	22.5
2004-07-01	21.6
2004-10-01	21.3
2005-01-01	21.7
2005-04-01	20.3
2005-07-01	18
2005-10-01	18.6
2006-01-01	18.7
2006-04-01	18.2
2006-07-01	16.9
2006-10-01	17.8
2007-01-01	17.7
2007-04-01	18.1
2007-07-01	17.9
2007-10-01	18.7
2008-01-01	21.1
2008-04-01	23.6
2008-07-01	24.2
2008-10-01	29
2009-01-01	35.5
2009-04-01	38.1
2009-07-01	38.6
2009-10-01	38.8
2010-01-01	40.7
2010-04-01	42
2010-07-01	40.6
2010-10-01	42.7
2011-01-01	45.3
2011-04-01	45.9
2011-07-01	45.6
2011-10-01	48.1
2012-01-01	51.7
2012-04-01	53
2012-07-01	52
2012-10-01	54.8
2013-01-01	56.9
2013-04-01	56
2013-07-01	54.1
2013-10-01	54.9
2014-01-01	55.5
2014-04-01	53.1
2014-07-01	52.4
2014-10-01	51.8
2015-01-01	51.4
2015-04-01	49.2
2015-07-01	46.6
2015-10-01	46.2
2016-01-01	46.5
2016-04-01	46.5
2016-07-01	41.9
2016-10-01	42.9
2017-01-01	41.7
2017-04-01	39.5
2017-07-01	36.0
2017-10-01	37.5
2018-01-01	36.3
2018-04-01	34.7
2018-07-01	33.0