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_16 (Id VARCHAR)
### Question:
Which 2008 had a 1998 and 2006 that were a when 2009 was sf?
### Answer:
SELECT 2008 FROM table_name_16 WHERE 1998 = "a" AND 2009 = "sf" AND 2006 = "a"