…For the first time ever, two-thirds of new phone acquirers are buying smartphones.

Smartphone use is exploding in the United States, while PC sales are dropping. If 66 percent of mobile phone buyers purchase smartphones, and 36.3-percent of them get the iPhone, then that means almost a quarter of all phones bought in the U.S. are iPhones. That also means 36 percent of the purchased phones run Android OS.

More from Nielsen, including the incredibly skewed graphic, is below—which gives Symbian, Palm and Windows 7 devices almost the same amount of “fill” at 2.8-percent as Apple’s 34 percent.