In the case of a contribution that is made under a mistake of fact, nothing in this part shall prohibit the return of that contribution within one year after discovery of the mistake.

The net earnings of the fund shall be allocated to the participant’s account as of each valuation date in the ratio that the participant’s account balance bears to the aggregate of all participants’ account balances.

The value of each participant’s account shall be determined at least once annually in a manner prescribed by the board.

A participant shall receive a statement that displays the value, or balance, of the participant’s account and summarizes any credits to the account or other transactions that occurred after the immediately preceding valuation date. The statement of account shall be provided at least once annually to each participant.