CREATE TABLE "fleet_details" (
  "class" text,
  "type" text,
  "introduced" text,
  "fleet_size" real,
  "numbers" text
);

Question: What is the fleet size of the Vanguard 0-6-0dh class?
SQL: SELECT "fleet_size" FROM "fleet_details" WHERE "class"='vanguard 0-6-0dh';

Question: What is the year of introduction for the Electro-Diesel locomotive?
SQL: SELECT "introduced" FROM "fleet_details" WHERE "type"='electro-diesel locomotive';

Question: What is the average fleet size for the Shunter type introduced in 1959?
SQL: SELECT AVG("fleet_size") FROM "fleet_details" WHERE "type"='shunter' AND "introduced"='1959';

Question: What is the smallest fleet size with a type of shunter introduced in 1953?
SQL: SELECT MIN("fleet_size") FROM "fleet_details" WHERE "type"='shunter' AND "introduced"='1953';