what was the number of patients receiving excise bone for gft nec since 2101?
select count( distinct admissions.subject_id ) from admissions where admissions.hadm_id in ( select procedures_icd.hadm_id from procedures_icd where procedures_icd.icd9_code = ( select d_icd_procedures.icd9_code from d_icd_procedures where d_icd_procedures.short_title = 'excise bone for gft nec' ) and strftime('%y',procedures_icd.charttime) >= '2101' )