According to the WHO, over 1.24 million people die every year due to traffic accidents. But accident rates vary significantly between countries. Roads Kill, an amazing interactive built by the Pulitzer Center, maps countries based on their accident fatality rates:
As the map shows, road-traffic deaths are a huge problem in developing nations. They are also the leading cause of death globally for people between the ages of 10-24 and the world's ninth leading cause of death overall.
China and India, with their large populations, account for little over half a million deaths every year, but they don't have the highest accident death rates. Casualties are more prevalent in developing countries, which accounted for 90 percent of traffic fatalities annually, despite accounting for only 50 percent of the world's total road traffic.
Traffic accidents have significant economic costs as well. According to a National Research Council / Institute of Medicine report, "the annual cost of road injuries worldwide is 1 percent of gross domestic product in low-income countries and 1.5 percent in middle-income countries." Safety laws aren't strictly enforced in many developing countries, nor are vehicles designed to the same standards as in developed countries.