CREATE TABLE table_57524 ("Class" TEXT, "Type" TEXT, "Introduced" TEXT, "Fleet Size" FLOAT, "Numbers" TEXT)

What is the fleet size of the Vanguard 0-6-0dh class?
SELECT "Fleet Size" FROM table_57524 WHERE "Class" = 'vanguard 0-6-0dh'
SELECT "Fleet Size" FROM "table_57524" WHERE "Class" = 'vanguard 0-6-0dh'