The Department shall submit for publication quarterly in the Illinois Register an index of any informal rulings, opinions or letters issued by the department during the quarter and required to be made available by Section 3. The Department shall also submit on or before January 15, 1982, and annually thereafter, for publication in the Illinois Register, a cumulative index of all such informal rulings, opinions or letters issued by the Department during the preceding calendar year. The cumulative index shall be made available to the public at cost. Such indexes shall include a brief synopsis of each informal ruling, opinion or letter together with information on how the public may gain access to such document.
20 ILCS 2515/4