For all the set of cards that has Brazil Portuguese translation, what is the percentage of them are only available online?
Brazil Portuguese translation refers to language = 'Portuguese (Brazil)'; only available online refers to isOnlineOnly = 1; percentage of online only Brazil Portuguese in all Brazil Portuguese cards refers to DIVIDE(SUM(isOnlineOnly = 1), SUM(language = 'Portuguese (Brazil)))*100
SELECT CAST(SUM(CASE WHEN isOnlineOnly = 1 THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(id) FROM sets WHERE code IN ( SELECT setCode FROM set_translations WHERE language = 'Portuguese (Brazil)' )