a) (Left panel) Same as Fig. 6a, but showing the revised two-function power law fit to normal galaxies (gray line) and luminous infrared galaxies (black line) discussed in Sect. 6.3. Symbols and errorbars as in Fig. 6. b) (Right panel) We show the revised depletion time scale as a function of derived in normal and luminous infrared galaxies, as discussed in Sect. 6.3. The dashed and continuous horizontal lines indicate the average value of the depletion time scale in normal galaxies (t_dep ~ 50 ± 5 Myr) and LIRGs/ULIRGs (t_dep ~ 14 ± 1.4 Myr). Symbols and errorbars as in Fig. 5.