CREATE TABLE table_203_406 (id DECIMAL, "entrant" TEXT, "constructor" TEXT, "chassis" TEXT, "engine" TEXT, "tyre" TEXT, "driver" TEXT, "rounds" TEXT)

how many drivers drove all the rounds ?
SELECT COUNT("driver") FROM table_203_406 WHERE "rounds" = 'all'
SELECT COUNT("driver") FROM "table_203_406" WHERE "rounds" = 'all'