On average, how many scenes are there in each of the comedy works written by Shakespeare?
comedy refers to GenreType = 'Comedy'; average = divide(sum(count(Scene)), count(work.id))
SELECT CAST(SUM(T2.Scene) AS REAL) / COUNT(T1.id) FROM works AS T1 INNER JOIN chapters AS T2 ON T1.id = T2.work_id WHERE T1.GenreType = 'Comedy'