Year	Number
1971	49822
1972	54302
1973	54979
1974	58455
1975	57621
1976	69812
1977	70663
1978	78060
1979	87148
1980	92603
1981	94000
1982	98422
1983	107479
1984	112428
1985	115642
1986	118442
1987	123310
1988	119280
1989	130777
1991	134081
1992	120063
1993	131271
1996	145455
1999	141479
2000	170141
2003	220366
2004	211136
2007	286890