Only about 1 in 8 people globally lives in a large (> 10 million people) city.
Most people who live in cities are in cities with < 250,000 people.
Exactly how many live in cities at all is determined by where you drawn the cutoff at which it's no longer a city.
And my answer to that is, if your area where people live isn't able to support a bus line, it's not a city. That means there's a lot of reality big towns out there.