Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
I want the total number of gross tonnage when entered service was 1903

### Inputs:
table_name: table, columns: ["Ship's name", 'Entered service', 'Ended service', 'Gross Tonnage', 'Type of Vessel']

### Response:
SELECT COUNT Gross Tonnage FROM table WHERE Entered service = 1903