Using U.S. Air Force weather satellite picture composites, they look at changes in a region’s light density over a 10-year period. “Consumption of nearly all goods in the evening requires lights,” ... “As income rises, so does light usage per person, in both consumption activities and many investment activities.” ... For example, in the Democratic Republic of Congo, lights suggest a 2.4-percent annual growth rate in GDP, while official estimates suggest a negative 2.6-percent growth over the same time period. The Congo appears to be growing faster than official estimates suggest. At the other end, Myanmar has an official growth rate of 8.6 percent a year, but the lights data imply only a 3.4-percent annual growth rate.