How many votes did Wales cast when Northern England cast 6?
CREATE TABLE "voting" (
  "song" text,
  "mobiles" real,
  "northern_ireland" real,
  "northern_england" real,
  "scotland" real,
  "southern_england" real,
  "wales" real,
  "total" real
);
SELECT MIN("wales") FROM "voting" WHERE "northern_england"=6;