Definition: In this task, you are given a statement spoken by a politician in natural language. Your task is to generate the subject of the discussion for the given statement. The subject generated is not necessarily a part of the given input. Your answer should contain one or more words.
Input: Since 2008, U.S. crude oil output has increased by over 80 percent, an increase of over 4 million barrels a day. That is the fastest increase in U.S. history.

energy