Star formation efficiency as a function of stellar mass for the CO-VG sample (left) and the CO-CS (right) sample. Galaxies are colour coded according to their position on the SFMS as described in Fig. 3. The mean logarithm of the SFE per M_⋆ bin is shown with a blue dashed line for the CO-VG and a blue solid line for the CO-CS sample, considering only those galaxies that belong to the SFMS. The extent of this line represent the width of the stellar mass bin. The error of the mean value is represented with a grey shadow. The lower limits are shown with upward-pointing arrows.