Commencing October 1, 2000, beneficiaries of pensioners formerly participating in a retirement program of a Class 1 municipality but whose benefits are currently administered by the Employees’ Retirement System shall receive a monthly increase of thirty-five dollars ($35) provided the local public board elects to fund the increase. All other beneficiaries of Employees’ Retirement System pensioners shall receive an increase of twenty-five dollars ($25) per month provided the local units elect to fund the increase.