Are there tables for successive ionization energies for metals (like for gases)? All I can find are work functions to remove one electron from the surface of a metal into vacuum (and to keep it there). However, I guess it gets harder to remove electrons the more electrons already have been removed, right? 

Maybe there's a way to relate that energy to the average degree of ionization of the material. Is it possible at all?

Finally, is it harder to ionize a metal gas or a metal solid? Although most work functions are a little bit smaller than the (1st) ionization-energies of the same material in gaseous state but I still think ionization of solids is harder. Am I correct?