7910172
 7920172
 7930172
 7940172
 7950172          Instrument out of operation
 7910272
 7920272
 7930272
 7940272
 7950272          1992 Coefficients in use
 7910372
 7920372
 7930372
 7940372
 7950372          1992 Coefficients in use
 7910472
 7920472
 7930472
 7940472
 7950472          1992 Coefficients in use
 7910572
 7920572
 7930572
 7940572
 7950572          1992 Coefficients in use
 7910672
 7920672
 7930672
 7940672
 7950672          1992 Coefficients in use
 7910772
 7920772
 7930772
 7940772
 7950772          1992 Coefficients in use
 7910872
 7920872
 7930872
 7940872
 7950872          1992 Coefficients in use
 7910972
 7920972
 7930972
 7940972
 7950972          1992 Coefficients in use
 7911072
 7921072
 7931072
 7941072
 7951072          1992 Coefficients in use
 7911172
 7921172
 7931172
 7941172
 7951172          1992 Coefficients in use
 7911272
 7921272
 7931272
 7941272
 7951272          1992 Coefficients in use