question: What year did a change in DST policy cost North America somewhere between $ 500 million and $ 1 billion in extra work ?
answer: 2007
turker_answer: A change in DST policy cost North America somewhere between $ 500 million and $ 1 billion in extra work in 2007 .
rule-based: 2007 did a change in DST policy cost North America somewhere between $ 500 million and $ 1 billion in extra work .