i've just viewed the impact graph (https://github.com/aburch/simutrans/graphs/impact) for simutrans on github. While the code is a highly collaborative project, it is astounding how much work prissi put into it.
During long periods, he was the only active developer and he usually uploads patches created by other people who are not part of the development team like z9999, inkelyad,isidoro, Frank, etc... thus the figures seem reasonable to me.
The impact graph is a little bit biased :) I think one of the larger commits of prissi (changing some 100k of code) were actually changes in the font file cyr.bdf. But yes he did a lot of work for simutrans.
Not to mention the first commits are from zip files, because the old SVN was lost and are not from Christoph but rather from Hajo, me, Dario and Hendrik (which contributed when I started to contribute too). But working on this for now 6 years gives some impact ;)
Luckily the situation recently became better, as you can see. I am very grateful for that.
EDIT: THe punchcard tells clearly, when the european start the work ...