Difference of the significance, Δσ, of the AGN fraction estimations with and without X-ray information, for sources with L_X >  10⁴⁵ erg s⁻¹ and difference in frac_AGN >  0.2 (shaded histogram) and sources with L_X <  10⁴³ erg s⁻¹ and difference in frac_AGN <  −0.2. The statistical significance of the AGN fraction measurements improves significantly with the inclusion of the X-ray flux, especially for the most luminous AGNs.