แผนกส่วนใหญ่ก่อตั้งในปีไหน?ไม่จำเป็นต้องใช้ตารางทั้งหมด
In which year were most departments established?It is not neccessary to use all the tables.
 department:  (creation [ VARCHAR) ]
SELECT creation FROM department GROUP BY creation ORDER BY COUNT(*) DESC LIMIT 1