There's no way to compute an approximation here since reports of ball lightning are so infrequent. "Populated area" is somewhat subjective here since those tha

There's no way to compute an approximation here since reports of ball lightning are so infrequent. "Populated area" is somewhat subjective here since those that live in a rural, open area, especially the prairies, are able to observe more lightning activity. Most of the reports that I've read about involve those living in the country where the artifact of the strike, the resulting ball, can be readily observed. I'd read about a laboratory trying to recreate this phenomenon using submarine batteries and were more successful in blowing the roof off the warehouse than creating ball lightning.