I asked one of my history professors about this on Friday, and he said he didn't know the answer; however, he indicated that perhaps the sentencing was done this way because otherwise there would have been almost nobody left. At any rate, what I am wondering is if there is a database of sorts in existence that holds information about [camp and] Nazi officials and their war crime trials' results/sentencing. I am tempted to start my own database (and indeed I will probably start soon) because it's rather maddening. Fifteen years, for example, seems like a slap on the wrist, and I have seen that length of time given a few times, mostly in Goldensohn's "The Nuremberg Interviews" or perhaps I had read it elsewhere. Altogether, my professor cautioned me that "well, life isn't fair", but I do wonder how is it that people these days are sentenced to life in prison yet people then--definitely guilty of war crimes, etc--were not given such a sentence. I have begun the process of speaking with the Holocaust Museum that is closest to me: I'm hoping to find someone that can actually answer my questions without treating me as if my passion for history is flighty.
What are you exactly looking for?, compiling that sort of statistics looks like a multi man years work to me. Contacting the Wiesental Institute or just looking through their book catalogue, might be a good stating point if you are looking at just the Holocaust. If you want to look at all war crimes, it's a a huge subject, and I have done practically no research on in myself so I would not know where to start, the risk of ending up comparing apples and oranges is significant if you assemble data from different sources.