An aircraft model was tested in a low speed wind-tunnel (Reynolds number =2×10⁶ based on wing mean chord). The variation of pitching moment coefficient (C_m) with angle of attack (α) for two elevator deflections (δ_e) as recorded during this test is presented below. Based on the result presented in the figure above, the value of elevator control power (C_mδe) in per radian will be _______ (in three decimal place).