(1) A member of the retirement system shall receive a retirement allowance equal to one percent of such member's average final compensation for each service credit year.

(2) The retirement allowance payable under RCW 41.40.820 to a member who separates after having completed at least twenty service credit years shall be increased by twenty-five one-hundredths of one percent, compounded for each month from the date of separation to the date that the retirement allowance commences.