SELECT AVG(year) FROM table_name_93 WHERE beer_name = "maggs magnificent mild" AND prize = "gold medal" AND category = "mild and porter" AND competition = "siba south east region beer competition"
What year did maggs magnificent mild win a gold medal in the mild and porter category at the siba south east region beer competition?
CREATE TABLE table_name_93 (
    year INTEGER,
    competition VARCHAR,
    category VARCHAR,
    beer_name VARCHAR,
    prize VARCHAR
)