Instruct: 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?
Output: SELECT AVG Effic FROM table WHERE Avg/G > 3.7 AND GP-GS = 13 AND Cmp-Att-Int = 318-521-15