Calculate the average number of current male legislators who chose Democrat from 2000 until 2021.
male refers to gender_bio = 'M'; legislators who chose Democrat refers to party = 'Democrat'; from 2000 until 2021 refers to start > = 2000 AND END < = 2021; calculation = DIVIDE(COUNT(bioguide_id), 22)
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'