China's new-energy vehicle industry is growing rapidly as vehicles with combustion-based engines have been identified as a major source of air pollution in many Chinese cities. Oil security is another motivation for the rising demand for electric vehicles in China, as imported oil accounts for 70 percent of the country's total oil consumption. By 2017, the cumulative sales of new-energy vehicles reached 1.8 million in China, accounting for over 50 percent of the global figure.