The LEGO set became a standard of creative play for children worldwide, unlocking the creativity to build vehicles, buildings, cities and more. Historians point to the invention of the wheel as a major turning point in world history. The invention of the LEGO wheel had the same monumental effect in the history of LEGO, making it possible to create cars, trucks and eventually the LEGO train building set that is one of the most successful LEGO sets of all time. LEGO currently produces about 20 billion LEGO bricks a year and has sold over 400 billion LEGOs in their history -- enough for every person on the planet to have over 60 LEGOs each!