Top left: mass-radius diagram with contours built using the exoplanets sample from Fig. 8. Black dots represent planets with mass measurements at the > 3σ level of statistical significance. HD 5278 b is indicated by a large dark magenta star. The contours are color-coded in terms of relative occurrence. Top right: same plot in the planetary mass–stellar irradiation plane. Bottom left: same plot in the planetary density vs. stellar irradiation plane. Bottom right: same plot in the planetary density vs. mass plane.