how many times has a remov intralum trach fb been done until 2 years ago?
select count(*) from procedures_icd where procedures_icd.icd9_code = ( select d_icd_procedures.icd9_code from d_icd_procedures where d_icd_procedures.short_title = 'remov intralum trach fb' ) and datetime(procedures_icd.charttime) <= datetime(current_time,'-2 year')