Variation of the bump amplitude E_b. Symbols are the same as in Fig. 3 with crosses overplotted on sources with a secure detection of the bump. From left to right and top to bottom: E_b is plotted versus log (SFR), log (M_star), log (L_IR), the age of the old stellar population t₁ (Gyr), the age of the young stellar population log (t₂) (Gyr), the mass fraction of the young stellar population log (f_ySP), A_FUV (mag), the specific SFR log (SFR/M_star), and the redshift z.