Quarter	Percent
1999-01-01	29.8
1999-04-01	29.1
1999-07-01	28.8
1999-10-01	28.3
2000-01-01	28.4
2000-04-01	27.9
2000-07-01	28.3
2000-10-01	28.2
2001-01-01	27.3
2001-04-01	26.9
2001-07-01	26.2
2001-10-01	25.9
2002-01-01	25.6
2002-04-01	24.9
2002-07-01	25.4
2002-10-01	25.3
2003-01-01	25.6
2003-04-01	25.6
2003-07-01	24.9
2003-10-01	25.5
2004-01-01	25.1
2004-04-01	24.7
2004-07-01	24.4
2004-10-01	24.2
2005-01-01	23.5
2005-04-01	23.3
2005-07-01	22.5
2005-10-01	23
2006-01-01	21.8
2006-04-01	22
2006-07-01	22.5
2006-10-01	23.8
2007-01-01	24.4
2007-04-01	24.7
2007-07-01	24.2
2007-10-01	23.2
2008-01-01	22.8
2008-04-01	21.9
2008-07-01	20.7
2008-10-01	20.4
2009-01-01	18.8
2009-04-01	18.6
2009-07-01	18.7
2009-10-01	18.6
2010-01-01	17.5
2010-04-01	17.2
2010-07-01	17.5
2010-10-01	17.2
2011-01-01	16.1
2011-04-01	15
2011-07-01	14.3
2011-10-01	14.7
2012-01-01	15.7
2012-04-01	16
2012-07-01	16.1
2012-10-01	16
2013-01-01	17.6
2013-04-01	16.3
2013-07-01	15.7
2013-10-01	15.2
2014-01-01	15.6
2014-04-01	15.1
2014-07-01	17.3
2014-10-01	17.9
2015-01-01	18.3
2015-04-01	17.8
2015-07-01	18.3
2015-10-01	17.7
2016-01-01	17.3
2016-04-01	16.9
2016-07-01	18.5
2016-10-01	20.2
2017-01-01	20.6
2017-04-01	21.7
2017-07-01	20.8
2017-10-01	21.5
2018-01-01	20.4
2018-04-01	20.5