Detection fraction of the four observed deuterated species in the different evolutionary stages. Here the infrared dark cloud (IRDC) stage is divided into the two subsamples without and with an embedded point source at 24 or 70 μm, indicated in the caption as IRDC(wops) and IRDC(wps). The detection fractions are shown from left to right with infrared dark clouds without embedded point sources in red (IRDC(wops)), infrared dark clouds with embedded point sources (IRDC(wps)) in gray, high-mass protostellar objects (HMPO) in blue, hot molecular cores (HMC) in yellow and ultracompact Hii regions (UCHii) in black.