Year	Percent
1976	8
1977	9
1978	13
1979	13
1980	14
1981	15
1982	13
1983	13
1984	12
1985	11
1986	8
1987	8
1988	8
1989	8
1990	12
1991	11
1992	11
1993	9
1994	10
1995	11
1996	11
1997	13
1998	13
1999	4
2000	4
2001	4
2002	3
2003	3
2004	4
2005	6
2006	7