user: Question: What was the tonnage on 30 March 1943?
Columns: ['Date', 'Ship', 'Nationality', 'Tonnage', 'Fate']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['5 March 1942', 'Collamer', 'USA', 5112.0, 'Sunk']
SQL:

assistant: SELECT "Tonnage" FROM "Table" WHERE "Date" = '30 March 1943';