when did patient 53015 enter the hospital until 2104 for the last time via the phys referral/normal deli?
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