return me the number of papers published in the VLDB conference in each year .
SELECT COUNT ( DISTINCT t2.title )  ,  t2.year FROM publication AS t2 JOIN conference AS t1 ON t2.cid  =  t1.cid WHERE t1.name  =  "VLDB" GROUP BY t2.year;
SELECT COUNT ( DISTINCT t2.title )  ,  t2.year FROM publication AS t2 JOIN conference AS t1 ON t2.cid  =  t1.cid WHERE t1.name  =  "VLDB" GROUP BY t2.year;
[{'Nenhum': 'Nenhum resultado encontrado'}]