In addition to any compensation provided by the state, each member and the clerk of the jury commission in Blount County shall receive a supplemental salary in the amount of twenty dollars ($20) per day for each day spent in the discharge of his or her duties up to a maximum of 120 days per year to be paid out of the county treasury upon the warrant of the probate judge of the county upon satisfactory evidence that such service has been rendered. That part of the compensation of the members and the clerk of the jury commission not paid by the state shall be paid from the general fund of the county.