what is the average amount of hospital cost which includes a ck-mb index testing lab test during this year?
select avg(t1.c1) from ( select sum(cost.cost) as c1 from cost where cost.hadm_id in ( select labevents.hadm_id from labevents where labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'ck-mb index' ) ) and datetime(cost.chargetime,'start of year') = datetime(current_time,'start of year','-0 year') group by cost.hadm_id ) as t1