SELECT country FROM stadium GROUP BY country ORDER BY count(*) DESC LIMIT 1
Find the country that has the most stadiums.
[Schema (values) (types)]: | swimming |  swimmer : id (text) , name (number) , nationality (text) , meter_100 (text) , meter_200 (number) , meter_300 (text) , meter_400 (text) , meter_500 (text) , meter_600 (text) , meter_700 (text) , time (text) | stadium : id (text) , name (number) , capacity (text) , city (text) , country (number) , opening_year (text) | event : id (text) , name (number) , stadium_id (text) , year (text) | record : id (text) , result (number) , swimmer_id (text) , event_id (text);