A statewide grand jury shall be selected at random from the names of all prospective grand jurors appearing on current lists compiled pursuant to chapter 9 of Title 9. In selecting the jurors, the jury commissioner shall select from each county a number of grand jurors which shall bear to the total number of grand jurors to be selected the same proportion as the current number of voters from the county bears to the total current number of voters for the state as a whole. For purposes of this section, Providence and Bristol counties shall be considered one county, and the size of the statewide grand jury shall be considered as twenty-three (23) members; provided, the actual size of the statewide grand jury shall conform to the provisions of § 12-11-1 and Rule 6(a) of the Superior Court Rules of Criminal Procedure.