what is the daily average white blood cells level of patient 17462 in this month?
select avg(labevents.valuenum) from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 17462 ) and labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'white blood cells' ) and datetime(labevents.charttime,'start of month') = datetime(current_time,'start of month','-0 month') group by strftime('%y-%m-%d',labevents.charttime)