tell me the number of times that patient 5142 has received an bilirubin, total lab test in the previous month.
select count(*) from labevents where labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'bilirubin, total' ) and labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 5142 ) and datetime(labevents.charttime,'start of month') = datetime(current_time,'start of month','-1 month')