Best-fit functions of Eq. (2) (solid red line), Eq. (3) (dot-dashed brown line), and Eq. (4) (dashed light-blue line) at the four redshifts specified in each panel. Individual clusters are shown with empty gray circles, while the median values are shown with black squares. Error bars indicate σ_μ and σ_η. The residuals of the best-fit functions with respect to the median values are shown at the bottom of each panel.