instruction: what are the top three most frequent procedures among the patients who have 20s since 3 years ago?
response: SELECT d_icd_procedures.short_title FROM d_icd_procedures WHERE d_icd_procedures.icd9_code IN (SELECT t1.icd9_code FROM (SELECT procedures_icd.icd9_code, DENSE_RANK() OVER (ORDER BY COUNT(*) DESC) AS c1 FROM procedures_icd WHERE procedures_icd.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.age BETWEEN 20 AND 29) AND DATETIME(procedures_icd.charttime) >= DATETIME(CURRENT_TIME(), '-3 year') GROUP BY procedures_icd.icd9_code) AS t1 WHERE t1.c1 <= 3)