Except in those years for which an audit has been made or is about to be made by a representative of the State Auditor of Ohio, Council shall each year cause an annual audit of all the financial affairs of the municipality during the preceding year to be made by a certified public accountant not in the employ of the municipality, or financially interested in any transaction to be audited. Council may, in addition, cause other audits for any purpose to be made at any other time.