Which group of heath workers is the third largest?
return heath workers ;return groups of #1 ;return size of #2 ;return #2 where #3 is highest ;return #2 besides  #4 ;return #5 where #3 is highest ;return #5 besides  #6 ;return #7 where #3 is highest
['select', 'project', 'project', 'superlative', 'discard', 'superlative', 'discard', 'superlative']