Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_9 ( effic INTEGER, cmp_att_int VARCHAR, avg_g VARCHAR, gp_gs VARCHAR )

### Question ###
Which Effic is the average one that has an Avg/G larger than 3.7, and a GP-GS of 13, and a Cmp-Att-Int of 318-521-15?

### Accurate SQL ###

SELECT AVG(effic) FROM table_name_9 WHERE avg_g > 3.7 AND gp_gs = "13" AND cmp_att_int = "318-521-15"