Among all students, calculate the percentage of disabled students.
percentage = CONCAT(DIVIDE(MULTIPLY(COUNT(disabled.name), 100), (COUNT(person.name that is not in disabled.name))),'%');
SELECT CAST(COUNT(T2.name) AS REAL) * 100 / COUNT(T1.name) FROM person AS T1 LEFT JOIN disabled AS T2 ON T2.name = T1.name