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