Year	Percent
1972	4
1973	4
1974	5
1975	5
1976	5
1977	5
1978	5
1979	5
1980	5
1981	4
1982	4
1983	4
1984	4
1985	5
1986	8
1987	13
1988	15
1989	16
1992	15
1993	15
1994	68
1995	48
1996	19
1997	16
1998	18
1999	20
2000	11
2001	9
2002	9
2003	12
2004	14
2005	19
2006	20