What are the total freights in metric tonnes when the total transit passengers is 147791?
CREATE TABLE "2008_data" (
  "rank" real,
  "airport" text,
  "total_passengers" real,
  "pct_change_2007_2008" text,
  "international_passengers" real,
  "domestic_passengers" real,
  "transit_passengers" real,
  "aircraft_movements" real,
  "freight_metric_tonnes" real
);
SELECT "freight_metric_tonnes" FROM "2008_data" WHERE "transit_passengers"=147791;