Although Apple's iPhone and Google's Android represent 71 percent of smartphones in the U.S. market, the two operating systems drove 83 percent of all application downloads during the last 30 days according to new data issued by research firm Nielsen. Forty-four percent of U.S. subscribers now own smartphones, Nielsen reports, adding that smartphones represented 56 percent of all mobile phone purchases during the last three months.

Android continues to dominate the U.S. smartphone landscape, commanding 42.8 percent of the nationwide market as of the close of the third quarter of 2011, Nielsen reports. HTC leads all Android manufacturers with 15.0 percent market share, followed by Samsung Electronics at 10.4 percent and Motorola Mobility at 10.4 percent. Rival Android manufacturers account for 7.2 percent of the U.S. smartphone market.

Apple's iOS makes up 28.3 percent of all U.S. smartphones, followed by Research In Motion's BlackBerry at 17.8 percent. Microsoft's Windows Phone 7/Windows Mobile is next at 6.1 percent--HTC leads all Windows device manufacturers at 4.7 percent, followed by Samsung at 0.6 percent and Motorola Mobility at 0.2 percent. HP's mothballed webOS still accounts for 2.2 percent of U.S. smartphones, followed by Symbian at 1.7 percent.