Top panel: normalized counts (number of sources per bin divided by the total number of sources) vs. S_pk × d², for the Pandian et al. (2007, 2009) data (red dashed line), the MMBS masers exclusively associated with Hi-GAL sources (dot-dashed blue line), and our own results (solid black line), including new and known methanol masers. Bottom panel: normalized counts vs. S_pk × d² of the merged distributions of the Hi-GAL MMBS masers with our own masers (black, solid line), and the AMGPS (dashed red line).