Write SQL query to solve given problem: What is the ratio of males and females among historical legislators?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT CAST(SUM(CASE WHEN gender_bio = 'M' THEN 1 ELSE 0 END) AS REAL) / SUM(CASE WHEN gender_bio = 'F' THEN 1 ELSE 0 END) FROM historical