What is the average fleet size for the Shunter type introduced in 1959?
CREATE TABLE table_name_3 (fleet_size INTEGER, type VARCHAR, introduced VARCHAR)
SELECT AVG(fleet_size) FROM table_name_3 WHERE type = "shunter" AND introduced = "1959"
### Context: CREATE TABLE table_name_3 (fleet_size INTEGER, type VARCHAR, introduced VARCHAR) ### Question: What is the average fleet size for the Shunter type introduced in 1959? ### Answer: SELECT AVG(fleet_size) FROM table_name_3 WHERE type = "shunter" AND introduced = "1959"