Write SQL query to solve given problem: Calculate the ratio of unemployed students who have never been absent from school.. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT CAST(SUM(IIF(T2.month = 0, 1, 0)) AS REAL) * 100 / COUNT(T1.name) FROM unemployed AS T1 INNER JOIN longest_absense_from_school AS T2 ON T2.name = T1.name