So the stats for the UK are 30,000 active pilots for a population of 60,000,000. So i make that 0.05%.
And the US has 250,000 pilots for 250,000,000 people so thats your 0.1%.
And given these are two of the most pilot/aircraft dense countries in the world then for the 6 billion people in the world there's probably less than 1-2m pilots. (But that still a scary amount of ego for one small planet)
If you want to get into the really rare atmosphere ask how many of those 1-2 m people are willing to turn the aircraft upside down.