Distribution of the different spectral types in a luminosity and Eddington ratio (L/L_Edd) context. Left plot: bolometric luminosity L_bol vs. L/L_Edd. Squared symbols identify the samples of S07 (low-z) and of S17 (high-z sources). Vertical purple line indicates L/L_Edd = 1. Colour scheme is the same as in Fig. 4. Right plot: median values of the Eddington ratio separated into high-luminosity (log L > 47 erg s⁻¹) and low luminosity for each spectral type. We have included our own sources, along with the comparison samples. Error bars indicate the semi-interquartile range.