If years in the select are strings (kudos!), then it only stand to reason that they should be sorted alphabetically:
'nineteen eighteen, nineteen eighty, nineteen eighty-eight, nineteen eighty-five, nineteen eighty-four, nineteen eighty-nine, nineteen eighty-one, nineteen eighty-seven, nineteen eighty-six, nineteen eighty-three, nineteen eighty-two, nineteen eleven, nineteen fifteen, nineteen fifty, nineteen fifty-eight, nineteen fifty-five, nineteen fifty-four, nineteen fifty-nine, nineteen fifty-one, nineteen fifty-seven...'