(a) Each July 1 the State Police Retirement System shall redetermine the amount of each monthly benefit which has been payable by the system for at least twelve (12) full calendar months. The redetermined amount shall be payable for the following twelve (12) calendar months.

(b) Subject to the maximum stated in subsection (c) of this section, the redetermined amount shall be the amount of the benefit payable as of the immediately preceding July 1 increased by three percent (3%).

(c) In no event shall the redetermined amount be more than the amount of the benefit payable as of the immediately preceding July 1 multiplied by the following fraction:

(1) The numerator shall be the average of the consumer price index for the twelve (12) calendar months in the calendar year immediately preceding July 1, but in no event an amount less than the denominator; and

(2) The denominator shall be the average of the consumer price index for the twelve (12) calendar months in the second calendar year preceding the redetermination date.

(d)

(1) As used in this section, "consumer price index" means the Consumer Price Index for All Urban Consumers, as determined by the United States Department of Labor and in effect January 1, 1987.

(2) However, should the consumer price index be restructured subsequent to 1988 in a manner materially changing its character, the Board of Trustees of the State Police Retirement System, after receiving the advice of the actuary, shall change the application of the consumer price index so that, as far as is practicable, the 1986 intent of the use of the consumer price index shall be continued.