Molecular gas fractions plotted for the same ALPINE galaxies (red circles) and CO-detected MS SFGs with the same color coding per redshift bin as in Fig. 6. Top panel: molecular gas fractions shown as a function of redshift. The respective means, errors on the means, and standard deviations per redshift bin are indicated by the large black/gray crosses. The light-gray shaded area corresponds to the molecular gas fractions obtained by Béthermin et al. (2015) from FIR SED stacks. The f_molgas means per redshift bin show a steep increase from z = 0 to z ∼ 3.7, followed by a flattening toward higher redshift within the 1σ dispersion on the means. Bottom panel: molecular gas fractions restricted to z ∼ 1 − 5.9 SFGs and shown as a function of stellar mass. A strong dependence of f_molgas on M_stars is observed for CO-detected high-redshift galaxies and the ALPINE galaxies as well.