user: Question: Who won the Silver the Year Katie Curtis Unknown won the Bronze?
Columns: ['Year', 'Location', 'Gold', 'Silver', 'Bronze']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [2005.0, 'Herne Hill', 'Kate Cullen Ian Smith', 'Jo Tindley Colin Denman', 'Joy Nixon Derek Marloe']
SQL:

assistant: SELECT "Silver" FROM "Table" WHERE "Bronze" = 'Katie Curtis Unknown';