§ 69-b. Limitation on amount of variable rate debt instruments. As of the initial date of each issuance of variable rate bonds or the date of entering into any other variable rate debt instruments, or for debt issued on or before July first, two thousand five upon conversion of any state-supported debt to variable rate debt instruments, the total of the principal and notional amounts of such variable rate debt instruments outstanding and in effect shall not exceed an amount equal to fifteen percent of the total principal amount of state-supported debt outstanding.