Count the fastest superheroes.
fastest refers to attribute_value = 100 WHERE attribute_name = 'Speed';
SELECT COUNT(T3.superhero_name) FROM hero_attribute AS T1 INNER JOIN attribute AS T2 ON T1.attribute_id = T2.id INNER JOIN superhero AS T3 ON T1.hero_id = T3.id WHERE T2.attribute_name = 'Speed' ORDER BY T1.attribute_value DESC LIMIT 1