Gas-to-dust mass ratio, δ_GDR, of CO-detected galaxies with rest-frame λ_max ≥ 200μm, computed by combining CO-based gas masses and DL07-based dust masses. Symbols are as in Fig. 13. Left: δ_GDR as a function of metallicity. The red lines represent the local relation by Magdis et al. (2012) and its 0.15 dex scatter. Right: δ_GDR as a function of other relevant parameters: redshift z; depletion times based on CO; M^∗ (Wuyts et al. 2011a); and .