The board of supervisors shall be required to levy the annual tax of eighty-one cents per thousand dollars of assessed value of taxable property so long as the bonds are in arrears. [C39, § 5526.23; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §357.23 ] Referred to in §357.35