1992 26,570 vehicles 1991 35,584 vehicles 1990 49,567 vehicles 1989 44,236 vehicles 1988 19,938 vehicles 1987 16,715 vehicles 1986 18,049 vehicles 1985 23,742 vehicles 1984 31,075 vehicles 1983 27,889 vehicles 1982 26,390 vehicles 1981 13,733 vehicles 1980 18,797 vehicles