question: Find the total access count of all documents in the most popular document type.
#1 return documents 
#2 return types of #1 
#3 return number of  #1 for each #2 
#4 return #2 where #3 is  the  highest 
#5 return #1 where #2 is  #4 
#6 return access counts of #5 
#7 return sum of #6