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
What are the names of artist whose exhibitions draw over 200 attendees on average?
[Schema (values) (types)]: | theme_gallery |  artist : artist_id (text) , name (number) , country (text) , year_join (text) , age (number) | exhibition : exhibition_id (text) , year (number) , theme (text) , artist_id (text) , ticket_price (number) | exhibition_record : exhibition_id (text) , date (number) , attendance (text);