Year	Percent
1964	5
1965	5
1966	5
1967	5
1968	5
1969	5
1970	5
1971	5
1972	5
1973	5
1974	5
1975	5
1976	5
1977	5
1978	5
1979	5
1980	5
1981	9
1982	9
1983	9
1984	9
1985	9
1986	9
1987	9
1988	9
1989	9
1990	10
1991	20
1992	30
1993	29
1994	30
1995	30
1996	27
1997	32
1998	40
1999	74
2000	58
2001	57
2002	30
2003	300
2004	110
2005	540
2006	500