The Frankfurt Book Fair, the world’s largest gathering of the publishing industry, concluded on Sunday with gains in all categories. According to the organizers, by Sunday, 230,000 visitors had attended the world’s largest book fair. In the previous year, it had been 215,000. During the trade visitor days from Wednesday to Friday, 115,000 people reportedly visited the fair. The previous year, it had been 105,000. This year, they came from 153 countries. “Internationality is our hallmark,” said the fair’s director, Juergen Boos. For the first time, tickets for private visitors were capped over …