Semi-major axis (au) versus the f_q index for 661 JFCs (large square) and 646 JFC-like (2 < T_J < 3) fireballs collected by the DFN (hollow circle), EFN (hollow diamond), MORP (hollow square), and FRIPON (hollow triangle) networks. The coloration is indicative of the Kozai energy of the comet or meteoroid orbit at the observed epoch, where 0.7 is the critical limit where Kozai cycling of q–ω begins (Fernández et al. 2014).