Average annual salaries _before taxes_ in Western Europe starts between 30k EUR (Junior dev without a formal degree) and 40k EUR (Junior dev with a MS/engineering degree). I guess most people who started at 40k EUR finish their career between 60k EUR (as senior dev) and 80k EUR (as manager).
Then remove 25% as social charges + ~1 month of net salary as income tax + other various types of taxes.