Calculate the average percentage of word appearance in the page that have revision page id smaller than 106680.
revision page id smaller than 106680 refers to revision < 106680; word appearance refers to occurrences; DIVIDE(SUM(occurrences where revision < 106680), COUNT(occurrences)) as percentage;
SELECT CAST(SUM(T1.words) AS REAL) * 100 / SUM(T2.occurrences) FROM pages AS T1 INNER JOIN pages_words AS T2 ON T1.pid = T2.pid WHERE T1.revision < 106680
database name:db_id language_corpus
langs table langs Cols: language id dtype integer, language dtype text, locale dtype text, pages dtype integer, words dtype integer, 
pages table pages Cols: page id dtype integer, language id dtype integer, page dtype integer, revision dtype integer, title dtype text, words dtype integer, 
words table words Cols: word id dtype integer, word dtype text, occurrences dtype integer, 
langs_words table langs_words Cols: language id dtype integer, word id dtype integer, occurrences dtype integer, 
pages_words table pages_words Cols: page id dtype integer, word id dtype integer, occurrences dtype integer, 
biwords table biwords Cols: language id dtype integer, word id of the first word dtype integer, word id of the second word dtype integer, occurrences dtype integer, 
