Number of current pilots: Maybe the ICAO?
As for "future numbers": Be very careful because no one can predict that kind of thing. I've seen great numbers forecast, but then you find out the "study" that produced the future demand numbers was funded by industry lobby groups who have a vested interest in making things look "good".
The reality is the US and world-economy are really slowing down... most of the "forecasts" are based on the economy going up and up forever... how happy the universe would be if things went up and up forever...