Among the episodes which have star score greater than 5, how many episodes have air date in 2008?
star score greater than 5 refers to stars > 5; have air date in 2008 refers to air_date LIKE '2008%'
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) = '2008' AND T2.stars > 5;