Year	Number
1961	37
1962	43
1963	43
1964	43
1965	43
1966	44
1967	44
1968	44
1969	44
1970	45
1971	45
1972	45
1973	45
1974	46
1975	46
1976	46
1977	47
1978	46
1979	46
1980	45
1981	44
1982	44
1983	43