What's the oil rig of the song that ended on 7th place?
CREATE TABLE "national_final" (
  "draw" real,
  "artist" text,
  "song" text,
  "regions" real,
  "studio_audience" real,
  "press_jury" real,
  "oil_rig" real,
  "total_points" real,
  "place" text
);
SELECT "oil_rig" FROM "national_final" WHERE "place"='7th';