About two billion people will visit amusement parks this year to experience the thrilling rides they offer, according to the International Association of Amusement Parks and Attractions (IAAPA). Millions of guests will visit the 400 theme parks and attractions in the U.S. alone, generating about $55 billion. But having fun is a serious business. Most of the adventurers will have an amazing time but some will get hurt. The number of significant incidents has risen in most of America’s major theme parks, the Amusement Safety Organization reports.