tell me what are the top four most common output events until 3 years ago?
select d_items.label from d_items where d_items.itemid in ( select t1.itemid from ( select outputevents.itemid, dense_rank() over ( order by count(*) desc ) as c1 from outputevents where datetime(outputevents.charttime) <= datetime(current_time,'-3 year') group by outputevents.itemid ) as t1 where t1.c1 <= 4 )