Amazon rainforest oxygen output

[costaricarocks]

I've looked at several sites looking for the percentage of the earth's oxygen that the amazon rainforest produces. They all say a different number. Some say 50% of the earth's oxygen is provided by the amazon rainforest, some say 60%... the range I've seen so far is from 20% to 78%! Do any of you know a reliable source? Is it just that hard to figure out the real number? Thanks!

[forfismum]

Two words that might help you in your quest .Taiga and Phytoplankton.Both of these are far bigger generators of oxygen than the Amazon.And greater carbon sinks too come to think of it.