Year	Number
1961	1800
1962	1800
1963	1800
1964	1800
1965	1800
1966	1900
1967	2000
1968	2153.52
1969	2553.12
1970	2556.72
1971	2530.08
1972	2692.08
1973	2900.88
1974	2777.04
1975	3066.48
1976	3478.32
1977	3838.32
1978	3900
1979	3950
1980	3100
1981	4030
1982	4100
1983	4125
1984	4175
1985	4220
1986	4270
1987	4300
1988	4350
1989	4415
1990	4460
1991	4500
1992	4550
1993	4600
1994	4650
1995	4700
1996	4750
1997	4800
1998	4850
1999	4900
2000	4950
2001	5000
2002	5100
2003	5100
2004	5129