tell me what the total output on 12/18/2105 is for patient 28443.
select sum(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 = 28443 ) ) and strftime('%y-%m-%d',outputevents.charttime) = '2105-12-18'