What are the different affiliations, and how many schools with each have an enrollment size of above 20000?
return different affiliations ;return schools with  #1 ;return enrollment sizes of #2 ;return #2 where #3 is  higher than 20000 ;return number of  #4 for each #1 ;return #1 ,  #5
['select', 'project', 'project', 'comparative', 'group', 'union']