Oh I fully understand your question and it’s a very easy yes or no question to the question “Have you ever flown on an airplane” If you have flown, you would be considered a passenger (GA or commercial)
Being a passenger on an airplane is 1/2 equation to your question. (I can’t imagine anyone piloting a plane without ever being a passenger first).
I just don’t see how you can get a good reliable answer with the available data. I was hoping the census bureau would have had some type of “survey” have you ever taken a plane ride thus me poking my head extensively in their website…
The way passengers are counted now, with all that I saw, you won’t be able to differentiate between who has only flown once vs frequent fliers.
The passenger counts on commercial airlines are inflated for your question “how many people out of a certain population figure has flown”
Using airline passenger count is suspect in trying to figure out a percentage of a certain population that may have ever been on an airplane.
Your question doesn’t address commercial or GA, but that adds to the equation.
The percentage of people “who have flown” globally or on a national basis on commercial ONLY will be less then if you ask the question have you flown on GA **OR **commercial.
I have been focusing on USA data because that data is probably the most readily available “online” as a starting point. I realize the USA data is not indicative of the rest of the world, but clearly the rest of the world data may not be as comprehensive especially when you include third world countries where people could have been on a Caravan flight out of the bush.