Year	Percent
1985	0.01
1990	0.2
1991	0.3
1992	0.3
1993	0.3
1994	0.4
1995	0.4
1996	0.4
1997	0.4
1998	0.5
1999	0.5
2000	0.5
2001	0.5
2002	0.5
2003	0.5
2004	0.5
2005	0.4
2006	0.4
2007	0.4
2008	0.4
2009	0.4
2010	0.3
2011	0.3