What is the average number of pieces for boards that started in 1941 and were released after 2001?
CREATE TABLE "versions" (
  "release" real,
  "start" text,
  "pieces" real,
  "board_inches" text,
  "board_cm" text,
  "type" text
);
SELECT AVG("pieces") FROM "versions" WHERE "start"='1941' AND "release">2001;