what is the monthly average of arterial bp [diastolic] for patient 13528 in the first hospital visit?
select avg(chartevents.valuenum) from chartevents where chartevents.icustay_id in ( select icustays.icustay_id from icustays where icustays.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 13528 and admissions.dischtime is not null order by admissions.admittime asc limit 1 ) ) and chartevents.itemid in ( select d_items.itemid from d_items where d_items.label = 'arterial bp [diastolic]' and d_items.linksto = 'chartevents' ) group by strftime('%y-%m',chartevents.charttime)