Distributions of outflow detection rates and luminosity-to-mass ratios for the different subsamples of clumps. Top panel: outflow detection rate of clumps in different evolutionary stages and associated with different star-forming activities, as presented in Table 4. The error bars of each group are calculated from the binomial errors and the error of the detection rate for clumps with HC H II regions is adopted from the binomial errors of the total clump sample. Bottom panel: cumulative distributions of luminosity-to-mass ratios (L_bol ∕M_clump) for the subsamples of outflow clumps in the top panel, which indicate the evolutionary stages of these subsamples.