For each id of a driver who participated in at most 30 races, how many races did they participate in?
return drivers ;return ids of #1 ;return races #2 participated in ;return number of  #3 for each #2 ;return #2 where #4 is  at most 30 ;return races of #5 ;return number of  #6 for each #5
['select', 'project', 'project', 'group', 'comparative', 'project', 'group']