Year	Percent
1948	3
1949	3
1950	3
1951	4
1952	3
1953	3
1954	3
1955	3
1956	4
1957	5
1958	3
1959	4
1960	4
1961	4
1962	4
1963	4
1964	5
1965	5
1966	5
1967	5
1968	5
1969	6
1970	6
1971	5
1972	4
1973	8
1974	7
1975	5
1976	6
1977	5
1978	7
1979	10
1980	8
1981	9
1982	5
1983	5
1984	5
1985	5
1986	5
1987	4
1988	5
1989	7
1990	7
1991	9
1992	8
1993	5