Question: What's the rating of the episode in which Dan Castellaneta won the Outstanding Voice-Over Performance award in 2009?
SQL: SELECT T2.rating FROM Award AS T1 INNER JOIN Episode AS T2 ON T1.episode_id = T2.episode_id WHERE T1.award = 'Outstanding Voice-Over Performance' AND SUBSTR(T1.year, 1, 4) = '2009' AND T1.person = 'Dan Castellaneta';