what was the average rdw value for patient 58932?
select avg(labevents.valuenum) from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 58932 ) and labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'rdw' )