CREATE TABLE table_name_17 (destroyed INTEGER, survived VARCHAR(255), to_iran VARCHAR(255), damaged VARCHAR(255))
What's the average destroyed with a 1990 over 12, more than 1 damaged, 6 survivors, and a to Iran less than 4?
    
SQL: SELECT AVG(destroyed) FROM table_name_17 WHERE 1990 > 12 AND damaged > 1 AND to_iran < 4 AND survived = 6