Database: legislator
Question: Among the male legislators born between 1955 to 1965, what is the percentage of the legislators with an independent party?
SQL: SELECT CAST(SUM(CASE WHEN T2.party = 'Independent' THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(T2.party) FROM current AS T1 INNER JOIN `current-terms` AS T2 ON T1.bioguide_id = T2.bioguide WHERE T1.gender_bio = 'M' AND strftime('%Y', T1.birthday_bio) BETWEEN '1955' AND '1965'