§ 1209. Final average salary. For members who first become members of the New York state and local police and fire retirement system on or after April first, two thousand twelve, a member's final average salary shall be equal to one-fifth of the highest total wages earned by such member during any continuous period of employment for which the member was credited with five years of service credit; provided, however, if the wages earned during any year of credited service included in the period used to determine final average salary exceeds the average of the wages of the previous four years of credited service by more than ten percent, the amount in excess of ten percent shall be excluded from the computation of final average salary. Wages in excess of the annual salary paid to the governor pursuant to section three of article four of the state constitution shall be excluded from the computation of final average salary for members who first become members of the New York state and local police and fire retirement system on or after April first, two thousand twelve.