What is the average sales in billions of the company headquartered in France with more than 2,539.1 billion in assets?
CREATE TABLE "2012_list" (
  "rank" real,
  "company" text,
  "headquarters" text,
  "industry" text,
  "sales_billion" real,
  "profits_billion" real,
  "assets_billion" real,
  "market_value_billion" real
);
SELECT AVG("sales_billion") FROM "2012_list" WHERE "headquarters"='france' AND "assets_billion">'2,539.1';