Back to the Future for its influence in this regard. Examples can be seen in promotional material, in interviews in which professional skateboarders cite the film as an initiation into the action sport, and in the public's recognition of the film's influence. Tony Hawk has stated that “there are plenty of legendary pros that I know of that started skating because they saw that [film].” 1990s Skateboarding during the 1990s became dominated by street skateboarding. Most boards are about wide and long. The wheels are made of an extremely hard polyurethane, with hardness (durometer) approximately 99A. The wheel sizes are relatively small so that the boards are lighter, and the wheels' inertia is overcome quicker, thus making tricks more manageable. Board styles have changed dramatically since the 1970s but have remained mostly alike since the mid-1990s. The contemporary shape of the skateboard is derived from the freestyle boards of the 1980s with a largely symmetrical shape and relatively narrow width. This form had become standard by the mid-1990s. 2000s By 2001 skateboarding had gained so much popularity that more American people under the age of 18 rode skateboards (10.6 million) than played baseball (8.2 million), although traditional organized team sports still dominated youth programs overall. Skateboarding and skateparks began to be viewed and used in a variety of new ways to complement academic lessons in schools, including new non-traditional physical education skateboarding programs, like Skatepass and Skateistan, to encourage youth to have better attendance, self-discipline and confidence. This was also based on the healthy physical opportunities skateboarding was understood to bring participants for muscle & bone strengthening and balance, as well as the positive impacts it can have on youth in teaching them mutual respect, social networking, artistic expression and an appreciation of the environment. In 2003 Go Skateboarding Day was founded in southern California by the International Association of Skateboard Companies (IASC) to promote skateboarding throughout the world. It is celebrated annually on June 21 "to define skateboarding as the rebellious, creative celebration of independence it continues to be." According to market research firm American Sports Data the number of skateboarders worldwide increased by more than 60 percent between 1999 and 2002—from 7.8 million to 12.5 million. Many cities also began implementing recreation plans and statutes during this time period, as part of their vision for local parks and communities to make public lands more available, in particular, for