instruction: what were the three most commonly prescribed drugs for patients 20s until 2102?
response: SELECT t1.drugname FROM (SELECT medication.drugname, DENSE_RANK() OVER (ORDER BY COUNT(*) DESC) AS c1 FROM medication WHERE medication.patientunitstayid IN (SELECT patient.patientunitstayid FROM patient WHERE patient.age BETWEEN 20 AND 29) AND STRFTIME('%y', medication.drugstarttime) <= '2102' GROUP BY medication.drugname) AS t1 WHERE t1.c1 <= 3