Oh, I believe I knew this at one point in time. I'm a bit forgetful recently, but I do remember that quite a lot of oxygen is produced by the rainforest. I do not blame education for me not knowing, but my general interest and knowledge lies in technology and art. Mostly things they don't teach in school. What I do know is that algae do a lot, and I've heard and confirmed at one point that they produce around a third of the atmosphere's oxygen, though I am unsure. I tend to forget things I do not frequently recall.