how many patients were tested during this year for blood (toxo)?
select count( distinct admissions.subject_id ) from admissions where admissions.hadm_id in ( select microbiologyevents.hadm_id from microbiologyevents where microbiologyevents.spec_type_desc = 'blood (toxo)' and datetime(microbiologyevents.charttime,'start of year') = datetime(current_time,'start of year','-0 year') )