Among the" Mumbai Indians" team that played in 2009, how many percent of the matches did they win?
played in 2009 Match_Date like '2009%'; Mumbai Indians" team refers to Team_Name = 'Mumbai Indians'; percent of the matches did they win refers to DIVIDE(COUNT(Match_Winner = Team_Id), COUNT(Match_Id))
SELECT CAST(SUM(CASE WHEN T1.Match_Winner = T2.Team_Id THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(T1.Match_Id) FROM `Match` AS T1 INNER JOIN Team AS T2 ON T1.Team_1 = T2.Team_Id OR T1.Team_2 = T2.Team_Id WHERE T2.Team_Name = 'Mumbai Indians' AND T1.Match_Date LIKE '2009%'