instruction: how many patients had a microbiology blood, venipuncture test in this year?
response: SELECT COUNT(DISTINCT patient.uniquepid) FROM patient WHERE patient.patientunitstayid IN (SELECT microlab.patientunitstayid FROM microlab WHERE microlab.culturesite = 'blood, venipuncture' AND DATETIME(microlab.culturetakentime, 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-0 year'))