(b) In evaluating the amount of allowance to be granted, the statutory criteria (i.e., good behavior, efficient and willing performance of duties assigned, progress and achievement in an assigned treatment program) shall be viewed in the light of the following factors:

1. (1) the attitude of the inmate;
2. (2) the capacity of the inmate; and
3. (3) the efforts made by the inmate within the limits of his capacity.