1992 175 vehicles 1991 200 vehicles 1990 283 vehicles 1989 365 vehicles 1988 502 vehicles 1987 856 vehicles 1986 1,457 vehicles 1985 1,963 vehicles 1984 1,783 vehicles 1983 2,373 vehicles 1982 1,675 vehicles 1981 2,780 vehicles 1980 6,107 vehicles