The Nokia Lumia 521 is the most popular Windows Phone device in the USA, as it accounts for 27.4% of all smartphones, powered by the platform. Its peer, the Nokia Lumia 520, and Nokia's former flagship, the Lumia 920, are responsible for respectively 14.9% and 9.8% of all Windows Phone devices in 2013. With 7.3%, the HTC 8X is fifth, and is the only device to have succeeded in breaking up Nokia's monopoly of the platform.
Speaking globally, the successful Nokia Lumia 520 accounts for as much as 33% of all Windows Phone devices. The second place goes to the Lumia 920 with 7.4%, while the Nokia Lumia 620 gets receives a bronze medal with 7.0%. According to the report, the Nokia Lumia 720, Lumia 625, Lumia 710, and Lumia 820 are also quite popular.
Windows Phone statistics report
source: AdDuplex via WMPoweruser