How many people who were born after 1970 are animation executive producer?
born after 1980 refers to birthdate > 1970; assistant to the producers refers to role = 'animation executive producer'
SELECT COUNT(*) FROM Person AS T1 INNER JOIN Credit AS T2 ON T1.name = T2.person WHERE STRFTIME(T1.birthdate) > '1970' AND T2.role = 'animation executive producer';