(a) When the numerical count is marked on the container, containers are packed to weigh ten pounds or less, or in any container where the minimum diameter of the smallest apple does not vary more than 1⁄2 inch from the minimum diameter of the largest apple, percentages shall be calculated on the basis of count.
(b) In all other cases except those listed in paragraph (a) of this section, they shall be calculated on the basis of weight.