indicate the monthly maximum volume of drainage bag that patient 28048 has had until 05/2101.
select max(outputevents.value) from outputevents where outputevents.icustay_id in ( select icustays.icustay_id from icustays where icustays.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 28048 ) ) and outputevents.itemid in ( select d_items.itemid from d_items where d_items.label = 'drainage bag' and d_items.linksto = 'outputevents' ) and strftime('%y-%m',outputevents.charttime) <= '2101-05' group by strftime('%y-%m',outputevents.charttime)