From top to bottom abundances (with respect to the total H₂) of the analyzed molecules in the IRDC, HMPO, HMC and UCHii sample. The red line shows the median, the green cross is the mean, the bar indicates the inner 25%−75% range around the median and the whiskers mark the total range of all detections. The black arrows indicate the lowest upper limit of all calculated upper limits for this particular molecule and stage.