Among the male legislators born between 1955 to 1965, what is the percentage of the legislators with an independent party?
male refers to gender_bio = 'M'; born between 1955 to 1965 refers to strftime('%Y', birthday_bio) between '1955' and '1965'; percentage = MULTIPLY(DIVIDE(SUM(party = 'Independent' WHERE gender_bio = 'M' AND strftime('%Y', birthday_bio) between '1955' and '1965'), COUNT(party WHERE gender_bio = 'M' AND strftime('%Y', birthday_bio) between '1955' and '1965')), 100.0);
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'