Heavy-ion d$N_{\rm ch}/$d$\eta$ data (at midrapidity)  scaled by the degrees of freedom from a variety of initial state models. The dotted lines are to guide the eye. The circular markers represent d$N_{\rm ch}/$d$\eta$ divided by the number of participating nucleons in the MC Glauber nucleon model , diamonds use the number of constituent quarks from the MC Glauber constituent quark model , squares the entropy from T$_{\rm{R}}$ENTo , and stars the gluons from IP-Glasma .