710.5. The percentage to which section 710.4 refers in respect of a recognized gift with reserve of usufruct or use is (a) 87% where the duration of the usufruct or right of use provided for in the deed of gift granting it is 10 years or less;
(b) 74% where the duration of the usufruct or right of use provided for in the deed of gift granting it is more than 10 years and 20 years or less; and
(c) 61% in any other case.