China is on track to complete a three-year, $124-billion medical insurance initiative projected to cover more than 90% of its residents. Mexico completed an eight-year drive for universal coverage. Just 1% of the population of Thailand lacks health insurance. This push is leaving the U.S. behind. Some countries have gone with public systems, while others are relying on a mix of government and commercial insurance. “As countries advance, they are realizing that creating universal health-care systems is a necessity for long-term economic development,” said Julio Frenk, dean of the Harvard School of Public Health. China found that its citizens were saving excessively to protect them if they got seriously ill, said Yanzhong Huang, director of the Center for Global Health Studies at Seton Hall University. The high savings stifled demand for domestic consumer products, making the economy depend on selling goods abroad.