instruction: how much was the total hospital bill for patient 30733's stay in a year before?
response: SELECT SUM(cost.cost) FROM cost WHERE cost.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.subject_id = 30733) AND DATETIME(cost.chargetime, 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-1 year')