a) Histogram of the water maser luminosity in the 6.7 GHz methanol maser sample (Table 4. The dashed bars mark sources with the upper luminosity limits (non detections). b) Same as in a) but for the sources with ring-like distribution of methanol emission. c) Same as in a) but for the water maser sources not associated with the methanol masers. d) Histograms of methanol maser luminosity in the sample.