(1) Subject to this Act, a person who has attained the age of 65 years shall be entitled to retirement pension for any period of retirement if he satisfies the contribution conditions in section 89.
(2) The periods which shall be regarded for the purposes of this section as periods of retirement shall be specified by regulations.
"yearly average" means, in relation to any claimant, the average per contribution year of contribution weeks in respect of which that claimant has qualifying contributions, voluntary contributions or credited contributions in the period commencing either - (a) on the 5th day of January, 1953, in case the claimant is a man, or on the 6th day of July, 1953, in case the claimant is a woman, or (b) at the beginning of the contribution year in which the claimant's entry into insurance occurred (if after the 5th day of January, 1953, in the case of a man, or the 6th day of July, 1953, in the case of a woman) (whichever is the