user: Question: When was the historic place listed that's in Canyon county?
Columns: ['Name', 'Built', 'Listed', 'Location', 'County']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Boise River and Canal Bridge', '1922', '2007-02-07', 'Caldwell', 'Canyon']
SQL:

assistant: SELECT "Listed" FROM "Table" WHERE "County" = 'Canyon';