What's the average against of Leopold with more than 11 wins?
CREATE TABLE "2010_ladder" (
  "geelong_fl" text,
  "wins" real,
  "byes" real,
  "losses" real,
  "draws" real,
  "against" real
);
SELECT AVG("against") FROM "2010_ladder" WHERE "geelong_fl"='leopold' AND "wins">11;