Year	Number
1961	381
1962	581
1963	780
1964	980
1965	1180
1966	1379
1967	1579
1968	1778
1969	1978
1970	2178
1971	2377
1972	2577
1973	2777
1974	2976
1975	3176
1976	3375
1977	3575
1978	3775
1979	3974
1980	4174
1981	4120
1982	4067
1983	4013
1984	3959
1985	3906
1986	3852
1987	3798
1988	3744
1989	3691
1990	3637
1991	3583
1992	3530
1993	3476
1994	3422
1995	3476
1996	3858
1997	4241
1998	4623
1999	5006
2000	5388