Write SQL query to solve given problem: Calculate the average number of current male legislators who chose Democrat from 2000 until 2021.. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT CAST(COUNT(T1.bioguide_id) AS REAL) / 22 FROM current AS T1 INNER JOIN `current-terms` AS T2 ON T1.bioguide_id = T2.bioguide WHERE T1.gender_bio = 'M' AND CAST(T2.start AS DATE) >= 2000 AND CAST(T2.END AS DATE) <= 2021 AND T2.party = 'Democrat'