###HUMAN: give me the top four most common diagnoses since 1 year ago., ###ASSISTANT: SELECT t1.diagnosisname FROM (SELECT diagnosis.diagnosisname, DENSE_RANK() OVER (ORDER BY COUNT(*) DESC) AS c1 FROM diagnosis WHERE DATETIME(diagnosis.diagnosistime) >= DATETIME(CURRENT_TIME(), '-1 year') GROUP BY diagnosis.diagnosisname) AS t1 WHERE t1.c1 <= 4