How many Bangladeshi citizens are there in the borough ranked at number 7?
CREATE TABLE "asian_population_of_london" (
  "rank" real,
  "london_borough" text,
  "indian_population" real,
  "pakistani_population" real,
  "bangladeshi_population" real,
  "chinese_population" real,
  "other_asian_population" real,
  "total_asian_population" real
);
SELECT MIN("bangladeshi_population") FROM "asian_population_of_london" WHERE "rank"=7;