Without concrete numbers, we really cannot say anything. Its just speculation.

There is another way to see it. Your chances of passing are independent of other candidates in my opinion. You do not have to take the most marks to pass. You just have to secure the passing marks. There are many people who take more marks and still don't qualify because they failed one subject. So all you have to do is pass each subject. And to pass each subject, you really aren't competing with anyone. Its just you. If on the other hand, the amount of passing candidates was large, say 2000, and then you had to fight for the 200 or so vacancies, it would have been worth to calculate your chances of success. With the current passing rate though, nearly all the people that pass get allocated, so you just have to pass the exam. And in that, the other candidates do not play any role whatsoever.