I remember reading once that fewer than 5% of the world's population had ever flown on an aircraft.
I believe there are approximately 0.5 million powered aircraft operating in the world, and even if you assume 10 pilots per aircraft that would only yield 5 million pilots (i.e. less than 0.1% of the population). I doubt that adding in glider pilots would make a big difference. Even if you factor 3 or 4 ex-pilots per active pilot you'd struggle to get anywhere near 1%.