What percentage of students who enlisted in the navy make up the number of students enrolled in OCC?
in the navy refers to organ = 'navy'; enrolled in OCC refers to school = 'occ'
SELECT CAST(SUM(IIF(T1.school = 'occ', 1.0, 0)) AS REAL) * 100 / COUNT(T1.name) FROM enrolled AS T1 INNER JOIN enlist AS T2 ON T1.`name` = T2.`name` WHERE T2.organ = 'navy'