CREATE TABLE table_name_50 (win_average INTEGER, races_ridden VARCHAR(255), nationality VARCHAR(255), name VARCHAR(255))
What is the average win as a percentage of German racer Rudi Altig, who has ridden in over 79 races?
    
SQL: SELECT AVG(win_average) FROM table_name_50 WHERE nationality = "german" AND name = "rudi altig" AND races_ridden > 79