Some reference datas........

I^- < Br^- < S^2- < SCN^- < Cl^- < NO₃^- < F^- < OH^- < C₂O₄^2- < H₂O < NCS^- < CH₃CN < NH₃< en < bipy < phen < NO₂^- < PPh₃ < CN^- < CO

For the one like me:
The value of the ligand field splitting parameter, i.e. the amount by which the
degeneracy of the d-orbitals is disturbed by the effect of the electrostatic field generated
by the ligands, depends upon the identity of the ligands.

in simple terms how strong the ligands are?