I want to know the answer to the following question:
What year did a change in DST policy cost North America somewhere between $500 million and $1 billion in extra work?
All the background I'm provided with is that "For example, a 2007 North American rule change cost an estimated $500 million to $1 billion, and Utah State University economist William F. Shughart II has estimated the lost opportunity cost at around $1.7 billion USD.". Is that enough to answer the question?
Answer: yes