Which ICAO has a Fleet size of 2?
CREATE TABLE "commercial_airlines" (
  "airline" text,
  "icao" text,
  "iata" text,
  "callsign" text,
  "commenced_operations" real,
  "fleet_size" real,
  "headquarters" text
);
SELECT "icao" FROM "commercial_airlines" WHERE "fleet_size"=2;