what are the five most frequent output event during a year before?
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,'start of year') = datetime(current_time,'start of year','-1 year') group by outputevents.itemid ) as t1 where t1.c1 <= 5 )