All interest and other earnings on monies and investments of the retirement system shall be credited to the pension accumulation fund. The Board shall, at the end of each fiscal year, allow regular interest computed on members' individual balances in the pension savings fund at the beginning of the fiscal year, and on the mean balance in the pension reserve fund. The amount of interest so allowed and credited to the pension savings fund and pension reserve fund shall be charged to the pension accumulation fund.
(‘83 Code, § 36.58)