Dunkin’ Donuts added 18 stores over the last year to remain New York City’s largest national retailer, with 484 locations. The chain’s parent company, Dunkin’ Brands Group, is based in Canton. The sandwich shop Subway was number two, adding 24 stores to reach 454. Dunkin’s rival Starbucks was in third place. The figures were reported in the Center for an Urban Future’s annual study ranking the city’s retailers. The number of chain stores rose 3 percent from 2011.