CREATE TABLE table_203_201 (id DECIMAL, "class" TEXT, "type" TEXT, "ships" TEXT, "displacement" TEXT, "note" TEXT)

how many of the classes are type salvage tug ?
SELECT COUNT("class") FROM table_203_201 WHERE "type" = 'salvage tug'
SELECT COUNT("class") FROM "table_203_201" WHERE "type" = 'salvage tug'