(a) For purposes of this Code section, the term "highest average compensation" means the member's highest average monthly earnable compensation during a period of 24 consecutive calendar months while a member of the retirement system.

(b) Anything in this chapter to the contrary notwithstanding, every person who is in service in the Uniform Division of the Department of Public Safety as an officer, noncommissioned officer, or trooper, or as an officer or agent of the Georgia Bureau of Investigation on June 30, 1970, and every person who enters or reenters such service on or after July 1, 1970, may retire at any time after attaining the age of 55 and upon retirement such retiree shall receive the regular retirement benefits under this chapter, provided that he or she shall in any case receive a minimum monthly retirement benefit equal to 2 percent of his or her highest average compensation for each year of creditable service by filing an application therefor in a manner similar to that provided in Code Section 47-2-110.