Year	Percent
1970	8
1971	8
1972	8
1973	8
1974	8
1975	8
1976	8
1977	8
1978	8
1979	8
1980	8
1981	15
1982	15
1983	19
1984	23
1985	23
1986	23
1987	23
1988	23
1989	32
1990	35
1991	49
1992	49
1993	34
1994	45
1995	59
1996	46
1997	37
1998	62
1999	64
2000	13
2001	16
2002	15
2003	11
2004	10
2005	10
2006	9