how many procedures of vasc proc revision nec took place since 2104?
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 = 'vasc proc revision nec' ) and strftime('%y',procedures_icd.charttime) >= '2104'