Average trends of Hi mass fraction as a function of stellar mass, stellar mass surface density, concentration index and observed NUV − r color for the representative sample. In each panel, large circles indicate weighted average gas fractions (see text). These were computed including the non-detections, whose Hi mass was set to either its upper limit (dark green) or to zero (red). Green triangles are weighted medians. Only averages based on at least 8 galaxies are shown. These results are listed in Table 1. GASS data from Fig. 5 are shown in gray and green (for detections and non-detections, respectively). The dashed line in the first panel shows the Hi detection limit of GASS.