user: Question: I want the total number of gross tonnage when entered service was 1903
Columns: ["Ship's name", 'Entered service', 'Ended service', 'Gross Tonnage', 'Type of Vessel']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['Avalon', '13 June 1864', '1866', 613.0, 'Paddle steamer']
SQL:

assistant: SELECT SUM("Gross Tonnage") FROM "Table" WHERE "Entered service" = '1903';