Year	Percent
1997-12-31	7.4026
1998-12-31	6.8481
1999-12-31	5.3668
2000-12-31	6.1809
2001-12-31	4.8423
2002-12-31	4.2148
2003-12-31	3.6796
2004-12-31	4.7393
2005-12-31	4.5902
2006-12-31	4.8663
2007-12-31	5.7248
2008-12-31	4.36
2009-12-31	0.7747
2010-12-31	0.6776
2011-12-31	0.7019
2012-12-31	0.425