Every common carrier of passengers within the provisions of this chapter shall, whenever so requested by the department, file with the department a sworn statement showing the names of all persons within this state holding, or to whom during the preceding year such carrier issued, furnished, or gave a free ticket, free pass, free transportation, or a discriminating reduced rate, except wage earners of common carriers in their ordinary employment and families of such wage earners, and disclosing such further information as will enable the department to determine whether the person to whom it was issued was within the exception of said provisions.