7910171
 7920171
 7930171
 7940171
 7950171          Instrument out of operation
 7910271
 7920271
 7930271
 7940271
 7950271          1992 Coefficients in use
 7910371
 7920371
 7930371
 7940371
 7950371          1992 Coefficients in use
 7910471
 7920471
 7930471
 7940471
 7950471          1992 Coefficients in use
 7910571
 7920571
 7930571
 7940571
 7950571          1992 Coefficients in use
 7910671
 7920671
 7930671
 7940671
 7950671          1992 Coefficients in use
 7910771
 7920771
 7930771
 7940771
 7950771          1992 Coefficients in use
 7910871
 7920871
 7930871
 7940871
 7950871          1992 Coefficients in use
 7910971
 7920971
 7930971
 7940971
 7950971          1992 Coefficients in use
 7911071
 7921071
 7931071
 7941071
 7951071          1992 Coefficients in use
 7911171
 7921171
 7931171
 7941171
 7951171          1992 Coefficients in use
 7911271
 7921271
 7931271
 7941271
 7951271          1992 Coefficients in use