user: Question: Which route has 21 stations?
Columns: ['Line', 'Colour', 'Route', 'Length', 'Stations']
Types: ['text', 'text', 'text', 'text', 'real']
Sample row: ['U 1', 'red', 'Reumannplatz – Leopoldau', '14.6km (9.1mi)', 19.0]
SQL:

assistant: SELECT "Route" FROM "Table" WHERE "Stations" = 21.0;