user: Question: How many ranks by average for the couple Tana and Stuart?
Columns: ['Rank by average', 'Place', 'Couple', 'Total points', 'Number of dances', 'Average']
Types: ['real', 'real', 'text', 'text', 'real', 'text']
Sample row: [1.0, 1.0, 'Hayley & Daniel', '303.5', 12.0, '25.3']
SQL:

assistant: SELECT COUNT("Rank by average") FROM "Table" WHERE "Couple" = 'Tana and Stuart';