user: Question: How many route numbers occur for the origin of Birmingham and destination of Bristol?
Columns: ['Route Number', 'Origin', 'Intermediate stops', 'Destination', 'Provider']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [318.0, 'Birmingham', 'Cheltenham, Gloucester', 'Bristol', 'National Express']
SQL:

assistant: SELECT COUNT("Route Number") FROM "Table" WHERE "Origin" = 'Birmingham' AND "Destination" = 'Bristol';