Year	Percent
1951	4
1952	4
1953	4
1954	4
1955	4
1956	4
1957	4
1958	4
1959	4
1960	4
1961	4
1962	4
1963	4
1964	4
1965	4
1966	4
1967	4
1968	4
1969	4
1970	4
1971	4
1972	4
1973	4
1974	4
1975	5
1976	5
1977	5
1978	5
1979	5
1980	5
1981	6
1982	7
1983	7
1984	7
1985	8
1986	9
1987	9
1988	9
1994	7
1998	6
1999	5
2000	5
2001	5
2002	4
2003	3
2004	3
2005	3
2006	3