Shot Down Allied

What percentage of German fighters got shot down by Allied bomber gunners?
I don’t mean when the bombers had fighter escorts later in the war. I mean earlier in the war. Another way to ask the question is: In a fight between a fighter vs a bomber or fighters versus bombers in formation, what percentage of each is likely to get shot down?
I don’t think this question can be answered definitively. However, I remember reading that when US B-17s raided Schweinfurt, unescorted, they lost 60 out of the 261 (that figure is from memory) planes they sent out. This does not include planes that were damaged but made it back; neither does it take into account crew-men killed or injured these planes. Oh, and some of the 60 might have been downed by flak.
I have no idea how many planes the Germans put up – but they threw everything they had at the bombers. I believe they lost 120 aircraft of all types.
B-2 Shot Down over Yugoslavia in 1999 war