what was the number of times patient 28253 had a bicarbonate test in 2102?
select count(*) from labevents where labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'bicarbonate' ) and labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 28253 ) and strftime('%y',labevents.charttime) = '2102'