The chairman shall be paid an annual salary of $8,200 from the third Monday in January, 1979 to the third Monday in January, 1980; $8,700 from the third Monday in January, 1980 to the third Monday in January, 1981; $9,300 from the third Monday in January, 1981 to the third Monday in January 1982; $10,000 from the third Monday in January, 1982 to the effective date of this amendatory Act of the 91st General Assembly; and $25,000 thereafter, or as set by the Compensation Review Board, whichever is greater. Other members of the Commission shall each be paid an annual salary of $5,500 from the third Monday in January, 1979 to the third Monday in January, 1980; $6,000 from the third Monday in January, 1980 to the third Monday in January, 1981; $6,500 from the third Monday in January, 1981 to the third Monday in January, 1982; $7,500 from the third Monday in January, 1982 to the effective date of this amendatory Act of the 91st General Assembly; and $20,000 thereafter, or as set by the Compensation Review Board, whichever is greater. They shall be entitled to reimbursement for necessary traveling and other official expenditures necessitated by their official duties.