Year	Number
1961	29
1962	34
1963	34
1964	34
1965	35
1966	40
1967	45
1968	50
1969	55
1970	60
1971	65
1972	70
1973	75
1974	80
1975	85
1976	90
1977	95
1978	100
1979	110
1980	115
1981	120
1982	120
1983	120
1984	120
1985	120
1986	121
1987	423
1988	480
1989	660
1990	840
1991	1021
1992	1200
1993	1380
1994	1560
1995	1933