Among the episodes which have star score less than 8, how many episodes were aired in 2009?
star score less than 8 refers to stars < 8; aired in 2009 refers to air_date LIKE '2009%'
SELECT COUNT(DISTINCT T2.episode_id) FROM Episode AS T1 INNER JOIN Vote AS T2 ON T2.episode_id = T1.episode_id WHERE strftime('%Y', T1.air_date) = '2009' AND T2.stars < 8;