Give the average number of cities within markets that had a low market estimation larger than 10000?
return markets ;return low market estimations of #1 ;return #1 where #2 is  larger than 10000 ;return the  cities within #3 ;return the  number of  #4 for each #3 ;return the  average of #5
['select', 'project', 'comparative', 'project', 'group', 'aggregate']