Year	Percent
1997-01-01	3.36
1998-01-01	2.48
1999-01-01	2.62
2000-01-01	2.62
2001-01-01	2.95
2002-01-01	3.30
2003-01-01	3.42
2004-01-01	3.48
2005-01-01	4.08
2006-01-01	3.78
2007-01-01	3.78
2008-01-01	6.01
2009-01-01	6.43
2010-01-01	5.56
2011-01-01	5.42
2012-01-01	5.72
2013-01-01	6.03
2014-01-01	6.29
2015-01-01	6.35
2016-01-01	6.75