CREATE TABLE table_203_154 (id DECIMAL, "type" TEXT, "manufacturer" TEXT, "numbers" TEXT, "year built" DECIMAL, "quantity built" DECIMAL, "power  ( horsepower ) " DECIMAL, "max speed  ( km/h ) " DECIMAL, "note" TEXT)

what year was the first unit built according to this chart ?
SELECT MIN("year built") FROM table_203_154
SELECT MIN("year built") FROM "table_203_154"