How many known epidemics were known to occur before the revolt in the the Tepehuán region?
return known epidemics ;return the  revolt in  the   Tepehuán region ;return when  did #1 occur ;return when  was  #2 ;return #1 where #3 is lower than #4 ;return number of  #5
['select', 'select', 'project', 'project', 'comparative', 'aggregate']