I'd like to know what percentage of PhD candidates in Computer Science does not graduate with a PhD and thus drops out of their PhD program.
This number probably varies quite a bit for different countries (e.g., in Continental Europe one usually has to have a Master's degree before being eligible to start with a PhD, while in the US one can "drop out" with a Master's degree) and possibly also for different sub-fields; I'm mostly interested about German speaking countries (Germany, Austria, Switzerland) and PhD candidates with a focus in Algorithms and/or Theory, but any answer "x% in this subfield in that country/at that university" are also welcome.
Background story: Currently thinking hard whether I should go for a PhD in Algorithms at a German speaking university and not a 100% sure if it is the right thing for me. A professor (not the one I'd do the PhD with) urged me to at least give it a try and said that there is always the possibility to drop out if it isn't working out.