Among the users who obtained the "Teacher" badge, calculate their percentage of users
"Teacher" is the Name of badge;  percentage = Divide (Count(UserId where it's "Teacher"), Count(UserId)) * 100
SELECT CAST(COUNT(T1.Id) AS REAL) * 100 / (SELECT COUNT(Id) FROM users) FROM users AS T1 INNER JOIN badges AS T2 ON T1.Id = T2.UserId WHERE T2.Name = 'Teacher'