เรือส่วนใหญ่สร้างในปีใด?ไม่จำเป็นต้องใช้โต๊ะทั้งหมด
In which year were most of ships built?It is not neccessary to use all the tables.
 ship:  (built_year [ VARCHAR) ]
SELECT built_year FROM ship GROUP BY built_year ORDER BY COUNT(*) DESC LIMIT 1