user: Question: When Svein Tuft is the winner what is the highest stage?
Columns: ['Stage', 'Winner', 'General classification', 'Points classification', 'Mountains classification', 'Young rider classification', 'Team classification']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'Matthew Goss', 'Matthew Goss', 'Matthew Goss', 'Manuel Belletti', 'Michael Van Stayen', 'Team HTC-Columbia']
SQL:

assistant: SELECT MAX("Stage") FROM "Table" WHERE "Winner" = 'Svein Tuft';