There is no definitive evidence about the exact number of inmates killed, and therefore there will be no definitive evidence about the proportional make up. Many records were destroyed and what has survived is from many second hand sources.
Therefore the figures seem to vary widely: https://en.wikipedia.org/wiki/Mauthausen-Gusen_concentration...
But I am not writing for Washington Post and so my comments will not be widely read. So why do you ask for sources from me but not this article.