What is the % Change at London Heathrow airport?
CREATE TABLE "2004_final_statistics" (
  "rank" real,
  "airport" text,
  "location" text,
  "code_iata" text,
  "total_cargo_metric_tonnes" text,
  "2003_rank" text,
  "pct_change" text
);
SELECT "pct_change" FROM "2004_final_statistics" WHERE "airport"='london heathrow airport';