count the number of patients who have had a remove fb from periton procedure performed two or more times since 2104.
select count( distinct t1.subject_id ) from ( select admissions.subject_id, count(*) as c1 from procedures_icd join admissions on procedures_icd.hadm_id = admissions.hadm_id where procedures_icd.icd9_code = ( select d_icd_procedures.icd9_code from d_icd_procedures where d_icd_procedures.short_title = 'remove fb from periton' ) and strftime('%y',procedures_icd.charttime) >= '2104' group by admissions.subject_id ) as t1 where t1.c1 >= 2