Which GDP (nominal) has a Population of 5,550,239?
CREATE TABLE "prospective_members" (
  "country" text,
  "population" text,
  "area_km" text,
  "gdp_nominal" text,
  "gdp_per_capita_nominal" text
);
SELECT "gdp_nominal" FROM "prospective_members" WHERE "population"='5,550,239';