Find the names of stadiums whose capacity is smaller than the average capacity.
SELECT name FROM stadium WHERE capacity  <  (SELECT avg(capacity) FROM stadium)
SELECT name FROM stadium WHERE capacity  <  (SELECT avg(capacity) FROM stadium)
[{'name': 'Northumberland Development Project'}, {'name': 'Fisht Olympic Stadium'}, {'name': 'Arena Baltika'}, {'name': 'Yubileyniy Stadium'}]