how many patients have received a ck-mb index test since 2101?
select count( distinct admissions.subject_id ) from admissions where admissions.hadm_id in ( select labevents.hadm_id from labevents where labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'ck-mb index' ) and strftime('%y',labevents.charttime) >= '2101' )