What is the average amount of silver medals Montenegro, who has less than 15 bronze and more than 11 total medals, has?
CREATE TABLE "medal_table" (
  "nation" text,
  "gold" real,
  "silver" real,
  "bronze" real,
  "total" real
);
SELECT AVG("silver") FROM "medal_table" WHERE "bronze"<15 AND "nation"='montenegro' AND "total">11;