What's the average total cargo in metric tonnes that has an 11.8% Change?
CREATE TABLE "2009_final_statistics" (
  "rank" real,
  "airport" text,
  "code_iata_icao" text,
  "total_cargo_metric_tonnes" real,
  "pct_change" text
);
SELECT AVG("total_cargo_metric_tonnes") FROM "2009_final_statistics" WHERE "pct_change"='11.8%';