user: 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?
Columns: ['Name', 'GP-GS', 'Effic', 'Cmp-Att-Int', 'Avg/G']
Types: ['text', 'text', 'real', 'text', 'real']
Sample row: ['Reesing, Todd', '13-13', 148.52, '329-495-13', 299.1]
SQL:

assistant: SELECT AVG("Effic") FROM "Table" WHERE "Avg/G" > 3.7 AND "GP-GS" = '13' AND "Cmp-Att-Int" = '318-521-15';