(1) The board shall grant service credit pursuant to this section on an annual basis to members who participate during each fiscal year.
(2) Service credit shall be calculated as follows:
(a) For each year during which a member provides compensated service to one or more school districts for one thousand or more hours, the member shall be credited one year of service credit; and
(b) For each year during which a member provides less than one thousand hours of compensated service to one or more school districts, the member shall be credited one one-thousandth of a year's service credit for each hour worked.
(3) The board may adopt and promulgate rules and regulations for the granting of service credit in accordance with this section, but in no case shall more than one year of service be granted for all service in one plan year.