user: Question: When was the station WLS-TV owned since?
Columns: ['Market Rank & City of license /Market', 'Station', 'Channel TV / DT', 'Owned since', 'Affiliation']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['1. New York City', 'WABC-TV a station built and signed-on by ABC', '7 / 7', 1948.0, 'ABC']
SQL:

assistant: SELECT "Owned since" FROM "Table" WHERE "Station" = 'WLS-TV';