From Sharon - A Riddle

You are a bus driver. At the first stop of the day, eight people get on board. At the second stop, four get off, and eleven get on. At the third stop, two get off, and six get on. At the fourth stop, thirteen get off, and one gets on. At the fifth stop, five get off, and three get on. At the sixth stop, three get off, and two get on. What colour are the bus driver's eyes?