what is the monthly minimum amount of phosphate patient 8204 has since 06/2105?
select min(labevents.valuenum) from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 8204 ) and labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'phosphate' ) and strftime('%y-%m',labevents.charttime) >= '2105-06' group by strftime('%y-%m',labevents.charttime)