count the number of patients who have already undergone a bile microbiology test until 2101.
select count( distinct admissions.subject_id ) from admissions where admissions.hadm_id in ( select microbiologyevents.hadm_id from microbiologyevents where microbiologyevents.spec_type_desc = 'bile' and strftime('%y',microbiologyevents.charttime) <= '2101' )