Upper panel: the fractions of 3281, 1203, 3468, and 9207 blue galaxies within C7, C8, C9, and C10, respectively, as a function of the δ. The δ-bins correspond to the quartiles of the δ distribution for the whole sample and the fractions are normalised to the total number of galaxies in the same sub-class, i.e. for each sub-class, the fractions in δ bins sum up to 100%. The solid line corresponds to the weighted fit. The shaded stripes around lines display 1σ of the fit. The slope of the fit is given in the legend. Bottom panel: as for the top panel, but for the mass-matched sample. The M_star distribution for each blue sub-class is the same.