What is the average opening at Stadyum Samsun with a capacity smaller than 34,658?
CREATE TABLE "under_construction_stadium_s" (
  "stadium" text,
  "capacity" real,
  "city" text,
  "club" text,
  "opening" real
);
SELECT AVG("opening") FROM "under_construction_stadium_s" WHERE "stadium"='stadyum samsun' AND "capacity"<'34,658';