Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_6 (decile INTEGER, roll INTEGER)
### Question:
How many decile has a roll less than 20?
### Answer:
SELECT AVG(decile) FROM table_name_6 WHERE roll < 20