-- Database schema
| actor : ActorID [ INTEGER ] primary_key , Name [ TEXT ] , Date of Birth [ DATE ] , Birth City [ TEXT ] , Birth Country [ TEXT ] , Height (Inches) [ INTEGER ] , Biography [ TEXT ] , Gender [ TEXT ] , Ethnicity [ TEXT ] , NetWorth [ TEXT ] | movie : MovieID [ INTEGER ] primary_key , Title [ TEXT ] , MPAA Rating [ TEXT ] , Budget [ INTEGER ] , Gross [ INTEGER ] , Release Date [ TEXT ] , Genre [ TEXT ] , Runtime [ INTEGER ] , Rating [ REAL ] , Rating Count [ INTEGER ] , Summary [ TEXT ] | characters : MovieID [ INTEGER ] characters.MovieID = movie.MovieID , ActorID [ INTEGER ] characters.ActorID = actor.ActorID , Character Name [ TEXT ] , creditOrder [ INTEGER ] , pay [ TEXT ] , screentime [ TEXT ] |
-- -- What is the percentage of the USA actors that showed up in the credit list of movie "Mrs. Doubtfire"?

SELECT CAST(SUM(CASE WHEN T3.`Birth Country` = 'USA' THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(T3.`Birth Country`) FROM movie AS T1 INNER JOIN characters AS T2 ON T1.MovieID = T2.MovieID INNER JOIN actor AS T3 ON T3.ActorID = T2.ActorID WHERE T1.Title = 'Mrs. Doubtfire';