question: What are the names of artist whose exhibitions draw over 200 attendees on average?
#1 return artists 
#2 return exhibitions of  #1 
#3 return attendees of  #2 
#4 return number of  #3 for each  #1 
#5 return average of  #4 
#6 return #1 where #5 is  higher than 200 
#7 return names of  #6