17.—(1) The proportion referred to in paragraphs 9, 10, 12(c)(i) and (ii), 14 and 15 shall be calculated as follows—
where—
G is the number of days in the relevant year during which the company was a member of the group, and
H is the number of days in the relevant year.
(2) The proportion referred to in paragraph 16(a), (c) and (d) shall be calculated as provided in sub-paragraph (1) except that for this purpose G is the number of days in the relevant year during which the company was a member of the group in relation to which the calculation is being made.