What is the percentage of the set of cards that have Chinese Simplified as the language and are only available for online games?
are only available for online games refers to isOnlineOnly = 1; percentage = DIVIDE(COUNT(isOnlineOnly = 1),COUNT(isOnlineOnly))*100
SELECT CAST(SUM(CASE WHEN T2.language = 'Chinese Simplified' AND T1.isOnlineOnly = 1 THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(*) FROM sets AS T1 INNER JOIN set_translations AS T2 ON T1.code = T2.setCode