Year	Percent
1987	0.01018
1990	0.06
1991	0.06
1992	0.06
1993	0.1
1994	0.1
1995	0.1
1996	0.1
1997	0.2
1998	0.2
1999	0.3
2000	0.4
2001	0.5
2002	0.6
2003	0.7
2004	0.7
2005	0.8
2006	0.8
2007	0.9
2008	0.9
2009	0.7
2010	0.7
2011	0.7