Fraction of galaxies (stellar mass greater than 5 × 10⁸ h⁻¹ M_⊙) living in CGs (left) or that ever lived in one (right). Each analysis uses a neighborhood parameter NH = 50 ﹩{h}^{-1}﹩ kpc and a maximum shell density ratio ﹩{\mathrm{log}}_{10}({\rm{SR}})=-4﹩. These curves are the results of varying the mass ratio (MR = 0.05, red circles; MR = 0.10, orange squares; MR = 0.20, yellow triangles). The width of the shaded region is 50 times the Poisson uncertainty. In all cases, the fractions of galaxies in CGs peak at z ∼ 1.0–2.4 and drop off sharply at z ∼ 5 because of our dwarf galaxy cutoff mass. As expected, the most restrictive value of MR = 0.20 (with top-ranked galaxies of more comparable masses) results in fewer CGs at all redshifts.