what's the maximum cost of a hospital with levetiracetam this year?
select max(t1.c1) from ( select sum(cost.cost) as c1 from cost where cost.hadm_id in ( select prescriptions.hadm_id from prescriptions where prescriptions.drug = 'levetiracetam' ) and datetime(cost.chargetime,'start of year') = datetime(current_time,'start of year','-0 year') group by cost.hadm_id ) as t1