instruction: what were the five most commonly taken tests during this year for patients of age 20s?
response: SELECT t1.labname FROM (SELECT lab.labname, DENSE_RANK() OVER (ORDER BY COUNT(*) DESC) AS c1 FROM lab WHERE lab.patientunitstayid IN (SELECT patient.patientunitstayid FROM patient WHERE patient.age BETWEEN 20 AND 29) AND DATETIME(lab.labresulttime, 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-0 year') GROUP BY lab.labname) AS t1 WHERE t1.c1 <= 5