31% of U.S. teens surveyed planned to buy an iPhone in the next six months, up from 22% last Autumn and nearly double the 16% who wanted one a year ago. 14% already own an iPhone, up from 8% a year ago, but down a point from 15% six months ago. Of the 87% who own an MP3 player, 92% own an iPod. Only Microsoft, Sony and Sandisk showed up in the results with Apple, with 3% market share each. Of the 82% of teens who download music, 43% do it legally. Of those, 92% get their music from Apple’s iTunes Store.