1994 1,008 vehicles 1993 4,421 vehicles 1992 3,201 vehicles 1991 1,525 vehicles 1990 1,308 vehicles 1989 1,166 vehicles 1988 841 vehicles 1987 524 vehicles 1986 308 vehicles 1985 261 vehicles 1984 228 vehicles 1983 235 vehicles 1982 1,791 vehicles 1981 3,054 vehicles 1980 5,311 vehicles