Year	Percent
1981	0.01571
1990	0.3
1991	0.3
1992	0.3
1993	0.3
1994	0.3
1995	0.3
1996	0.3
1997	0.3
1998	0.3
1999	0.3
2000	0.3
2001	0.3
2002	0.3
2003	0.4
2004	0.4
2005	0.4
2006	0.4
2007	0.4
2008	0.4
2009	0.4
2010	0.4
2011	0.4