Skateboarding is the act of riding on or performing tricks with a skateboard. A person who skateboards is referred to as a skateboarder or skater. Skateboarding—often portrayed in the media as an extreme sport—can be a form of art, a hobby, or a method of transportation. Skateboarding has been shaped and influenced by many skateboarders throughout the years. A 2002 report by American Sports Data found that there were 12.5 million skateboarders in the world. Eighty percent of skateboarders polled who had used a board in the last year were under the age of 18, and 74 percent were male. Skateboarding is a relatively modern sport—it originated as "sidewalk surfing" in the United States—particularly California—in the 1950s. A key skateboarding trick, the ollie, was only developed in the late 1970s