CREATE TABLE table_55501 ("Ship's name" TEXT, "Entered service" TEXT, "Ended service" TEXT, "Gross Tonnage" FLOAT, "Type of Vessel" TEXT)

I want the total number of gross tonnage when entered service was 1903
SELECT COUNT("Gross Tonnage") FROM table_55501 WHERE "Entered service" = '1903'
SELECT COUNT("Gross Tonnage") FROM "table_55501" WHERE "Entered service" = '1903'