For joint projects described in subdivision (2)(a) of section 72-2303, the principal amount of bonds which may be issued by a qualified public agency under the Public Facilities Construction and Finance Act shall not exceed five million dollars as to the total principal amount of such bonds which may be outstanding at any time, and the annual amounts due by reason of such bonds from each qualified public agency shall not exceed five percent of the total revenue from all sources of the obligated qualified public agency in the year prior to issuance. The principal amount of bonds of qualified public agencies in the aggregate issued for any one such joint project shall not exceed five million dollars.