"Accounting book value" means the value carried on the accounting records of the township school treasurer as of the last day of a calendar quarter.
"Annual total compensation" means the total cost to taxpayers for the services of the identified individual during the most recently completed fiscal year.
"Investment instrument" means an individual investment security as provided for under the Uniform Commercial Code or the aggregate value of all shares held in an individual investment fund or pooled account.
"Investment rate of return" means:
105 ILCS 5/5-38