40.—(1) Where damages are awarded to any person by virtue of subsection (1) of section 34, the jury or if there is no jury then the judge or arbitrator shall find and record—

(a) the total damages that would have been awarded if there had not been contributory negligence;

(b) where the plaintiff’s damages are reduced under the said subsection, the proportion of such damages that shall not be awarded to the plaintiff and the proportion that shall be payable by the defendant, or the respective proportions that shall be payable by each of the defendants if more than one, expressed in each case in percentage of the total fault of the plaintiff and defendant or defendants;

(c) F11[…]

(2) It shall be the duty of the judge or arbitrator to make the requisite calculations following upon such findings.