Database: college_completion
Question: List the race of institutions in Alabama with number of students greater than the 90% of average number of students of all institutions?
SQL: SELECT DISTINCT T2.race FROM institution_details AS T1 INNER JOIN institution_grads AS T2 ON T2.unitid = T1.unitid WHERE T1.student_count > ( SELECT AVG(T1.student_count) * 0.9 FROM institution_details AS T1 INNER JOIN institution_grads AS T2 ON T2.unitid = T1.unitid WHERE T1.state = 'Alabama' ) AND T1.state = 'Alabama'