What is the percentage of the people who are under 35 and participated in the summer season?
DIVIDE(COUNT(age < 35) / COUNT(person_id)) as percentage where season = 'Summer';
SELECT CAST(COUNT(CASE WHEN T2.age < 35 THEN 1 END) AS REAL) * 100 / COUNT(T2.games_id) FROM games AS T1 INNER JOIN games_competitor AS T2 ON T1.id = T2.games_id WHERE T1.season = 'Summer'