What is the decile of the school with a roll larger than 513?
CREATE TABLE "central_otago_district" (
  "name" text,
  "years" text,
  "gender" text,
  "area" text,
  "authority" text,
  "decile" real,
  "roll" real
);
SELECT SUM("decile") FROM "central_otago_district" WHERE "roll">513;