[Lenny5160]

I don't think a % of anything is a good measure for predicting performance. You'd need an absolute measurement of the 'amount' of Oxygen in the air. I don't know how that is done.

Much like how most racers have moved away from Relative Humidity % and are now using Grains. Dew Point is essentially the same thing as Grains for ET prediction purposes, but on a different scale.