Normalized warm gaseous CH₃OH mass with respect to M_dust within a 200 au radius as a function of the bolometric luminosity. Sources around which a disk has been detected on >10 au scales are indicated in blue, and sources where no disk is confirmed on >50 au scales are indicated in red. All other sources (i.e., with no information about a disk) are shown in gray. The green line indicates the best-fit power-law model to the data points (excluding the upper limits) and the green shaded area the 3σ uncertainty on the fit. The yellow line indicates the relation for the toy model of Eq. (4) scaled to match the best-fit power-law model.