Abundances of the main sulfuretted species (H₂S, OCS, SO, SO₂) in each of the protostars in our sample. The purple marks represent the total sulfur abundance produced by these four sulfuretted molecules. Sources are sorted first by their Class and then by T_bol. Total abundances seem to present a slight growing trend with T_bol and Class. We find that with the data available, SO and SO₂ are tipically one to two orders of magnitude below H₂S and OCS, but optically thick lines (specially the H₂S lines not detected in ${\text{H}}_2^{33}\text{S}$) may play a role in refuting or supporting these findings. We note that H₂S and OCS abundances are very similar in IRAS2B and hardly distinguishable in the figure.