CREATE TABLE table_57527 ("Class" TEXT, "Type" TEXT, "Introduced" TEXT, "Fleet Size" FLOAT, "Numbers" TEXT)

What is the smallest fleet size with a type of shunter introduced in 1953?
SELECT MIN("Fleet Size") FROM table_57527 WHERE "Type" = 'shunter' AND "Introduced" = '1953'
SELECT MIN("Fleet Size") FROM "table_57527" WHERE "Introduced" = '1953' AND "Type" = 'shunter'