Think this is US only but if not might give a clue of how many Xbox ones have been sold
"Combined sales of PlayStation 4 and Xbox One continue on a record-setting pace," Piscatella said. "Over the first 50 months in market for each console, the combined hardware installed base of the PlayStation 4 and Xbox One now exceeds that of the PlayStation 3 and Xbox 360 by 18 percent, and that of the PlayStation 2 and Xbox by 4 percent."
"Combined sales of PlayStation 4 and Xbox One continue on a record-setting pace," Piscatella said. "Over the first 50 months in market for each console, the combined hardware installed base of the PlayStation 4 and Xbox One now exceeds that of the PlayStation 3 and Xbox 360 by 18 percent, and that of the PlayStation 2 and Xbox by 4 percent."