Number of resolvable sources (N_res) for as a function of e₀. Open dots represent median values from all the considered MBHB population models, while error bars represent the 84 and 16 percentile of the distribution. Blue points correspond to the results of 10-year MPTA data with S/N > 3, while the red ones represent the predictions for 30-year SKA data with S/N > 5. Orange points represent the 30-year SKA results but when accounting only for the white pulsar noise. The lower panel shows the eccentricity distribution of the whole MBHB population for different e₀ models (black) and the eccentricity distribution of the MBHBs detectable as CGW sources (e_rs) for SKA PTA (red) and for MPTA (blue). We note that all the distributions are normalised to the same peak value for visualisation purposes.