Worldwide production of mobile phones reached a record high in 2003. The number of mobile phones produced in the full year of 2003 topped 518,150,000 units, for a year-on-year increase of more than 24.4%, according to research by Nikkei Market Access. A combination of factors contributed to the surge in production. Handsets with color liquid-crystal screens boosted replacement buying, and demand continued to grow in China, the world's largest market for mobile phones. Mobile phones also took off in a major way in emerging markets such as India and Russia.