Which Founded  has a League of women's flat track derby association, and a Club of omaha rollergirls?
CREATE TABLE table_name_14 (founded INTEGER, league VARCHAR, club VARCHAR)
SELECT AVG(founded) FROM table_name_14 WHERE league = "women's flat track derby association" AND club = "omaha rollergirls"
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE table_name_14 (founded INTEGER, league VARCHAR, club VARCHAR) Question: Which Founded  has a League of women's flat track derby association, and a Club of omaha rollergirls? [/INST] SELECT AVG(founded) FROM table_name_14 WHERE league = "women's flat track derby association" AND club = "omaha rollergirls" </s>