what was the number of patients who had been prescribed prednisolone acetate 0.12% ophth. susp. until 2104?
select count( distinct admissions.subject_id ) from admissions where admissions.hadm_id in ( select prescriptions.hadm_id from prescriptions where prescriptions.drug = 'prednisolone acetate 0.12% ophth. susp.' and strftime('%y',prescriptions.startdate) <= '2104' )