1993 135 vehicles 1992 6,536 vehicles 1991 481 vehicles 1990 3,221 vehicles 1989 24,286 vehicles 1988 24,441 vehicles 1987 26,322 vehicles 1986 28,259 vehicles 1985 33,471 vehicles 1984 43,251 vehicles 1983 22,355 vehicles 1982 16,680 vehicles 1981 20,809 vehicles 1980 27,322 vehicles