Application of LCAO

If the lowest energy MO of HeH $^{+}$ has the following form: $\psi_{mol} = C_{1} \phi^{\text{H}}_{1s} + C_{2} \phi^{\text{He}}_{1s},$ do you expect $C_{2}$ to be larger or smaller than $C_{1}$ ?

Use the electron correlation diagram of HeH $^{+}$ .