Every insurance carrier writing insurance for liability hereunder, or the liability of employers rejecting this act, shall report to the commissioner of insurance, in accordance with such rules as he may adopt, such information as he may at any time require for the purpose of determining the solvency of the carrier or the fairness, reasonableness and adequacy of its rates, and for such purposes the commissioner of insurance may inspect the books and records of such carriers and examine its officers, agents and servants under oath.