Question: What are the names of artist whose exhibitions draw over 200 attendees on average?
SQL: SELECT T3.name FROM exhibition_record AS T1 JOIN exhibition AS T2 ON T1.exhibition_id  =  T2.exhibition_id JOIN artist AS T3 ON T3.artist_id  =  T2.artist_id GROUP BY T3.artist_id HAVING avg(T1.attendance)  >  200