what is the minimum monthly number of people diagnosed with benign neoplasm lg bowel during a year before?
select min(t1.c1) from ( select count( distinct diagnoses_icd.hadm_id ) as c1 from diagnoses_icd where diagnoses_icd.icd9_code = ( select d_icd_diagnoses.icd9_code from d_icd_diagnoses where d_icd_diagnoses.short_title = 'benign neoplasm lg bowel' ) and datetime(diagnoses_icd.charttime,'start of year') = datetime(current_time,'start of year','-1 year') group by strftime('%y-%m',diagnoses_icd.charttime) ) as t1