Skateboarding is an action sport that involves riding and performing tricks using a skateboard, as well as a recreational activity, an art form, an entertainment industry job, and a method of transportation. Skateboarding has been shaped and influenced by many skateboarders throughout the years. A 2009 report found that the skateboarding market is worth an estimated $4.8 billion in annual revenue, with 11.08 million active skateboarders in the world. In 2016, it was announced that skateboarding will be represented at the 2020 Summer Olympics in Tokyo. Since the 1970s, skateparks have been constructed specifically for use by skateboarders, freestyle BMXers, aggressive skaters, and very recently, scooters. However, skateboarding has become controversial in areas in which the activity, although illegal, has damaged curbs, stoneworks, steps, benches, plazas and parks.