So soon as may be after the receipt of any report under section 9(2) the Authority shall consider such report and shall consider any return under section 8 and either—
(a) assess the percentage of loss of ratoon mats suffered by each affected holding in respect of which a return under section 8 has been made; or
(b)
(i) define the areas within which are comprised affected holdings which have suffered an approximately similar percentage of loss, or
(ii) assess the average percentage of loss of ratoon mats suffered by affected holdings within each such area consequent upon the windstorm in respect of which the assessment is made.