6. A statement of the extent to which, in the opinion of the billing authority, and of each relevant major precepting authority and relevant levying body, any difference between the amount mentioned in paragraph 3(1)(d) or, as the case may be, paragraph 4(a) and the amount mentioned in paragraph 5 for the authority is attributable to—
(a)inflation,
(b)differences in the grants received or expected to be received with respect to the year,
(c)changes in the quantity of services provided by the authority or body, and
(d)differences in the income received or expected to be received by way of fees and other charges for its services with respect to the year.