instruction: when did patient 53015 enter the hospital until 2104 for the last time via the phys referral/normal deli?
response: SELECT admissions.admittime FROM admissions WHERE admissions.subject_id = 53015 AND admissions.admission_location = 'phys referral/normal deli' AND STRFTIME('%y', admissions.admittime) <= '2104' ORDER BY admissions.admittime DESC LIMIT 1