Do rune percentages stack

middle-earth-shadow-of-mordor

So I have two runes on my bow. One gives me a 19% chance to recover focus on headshot kills, the other gives me a 33% chance to recover focus on headshot kills. On my first playthrough I always replaced lower level runes with higher level ones because I didn't now if percentages stacked. I was wondering if they actually do stack or is using different levels of the same rune an inefficient build if they don't? So does that setup give me a 52% chance to recover focus or do runes proc independently, which means that using two different levels of the same rune is, pretty much, useless?

Best Answer

Via a now deleted comment by user Sean:

Runes do stack, however, the only ones that do not are the ones that specifically state that in their description