Year	Percent
1998-01-01	4.96
1999-01-01	5.43
2000-01-01	6.03
2001-01-01	6.38
2002-01-01	6.62
2003-01-01	7.09
2004-01-01	7.40
2005-01-01	8.03
2006-01-01	8.20
2007-01-01	8.14
2008-01-01	7.13
2009-01-01	7.91
2010-01-01	7.94
2011-01-01	7.86
2012-01-01	8.38
2013-01-01	9.08
2014-01-01	9.69
2015-01-01	9.62
2016-01-01	9.52