If a majority of all votes cast upon the question shall be for the issuing of bonds and the levying of an additional tax to pay the interest and principal of such bond, the county board shall issue and sell such amounts of said bonds as the Commission shall determine and certify, from time to time as being necessary to provide the means for accomplishing the purposes for which said bonds were voted. Such bonds shall be issued in conformity to the requirements and provisions of the resolution adopted for the purpose of calling said election, provided however the aggregate amounts of outstanding bonds issued under the provisions of this Act, shall at no time exceed 1% of the total value of all of the taxable property of the county as determined by the last assessment roll on which county general taxes was extended. The principal of such bonds shall be discharged within twenty years after the date of said election. Such bonds shall bear interest, payable semi-annually, at a rate that does not exceed that permitted in “An Act to authorize public corporations to issue bonds, other evidences of indebtedness and tax anticipation warrants subject to interest rate limitations set forth therein”, approved May 26, 1970, as now or hereafter amended. The proceeds from the sale of each issue of bonds shall be deposited in the county treasury and identified as “County Airports Bond Fund No. …..” Such proceeds shall be used only for the purposes stated in the resolution calling the election authorizing the issuing of said bonds, and as specified in the certificate of the Commission as in this section provided.