instruction: what were the four medicines most frequently prescribed last year?
response: SELECT t1.drug FROM (SELECT prescriptions.drug, DENSE_RANK() OVER (ORDER BY COUNT(*) DESC) AS c1 FROM prescriptions WHERE DATETIME(prescriptions.startdate, 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-1 year') GROUP BY prescriptions.drug) AS t1 WHERE t1.c1 <= 4