The NPD Group don’t provide sales numbers to the public anymore, but NPD analyst, Anita Frazier, specifically pointed out in her report that Kid Icarus: Uprising, released on March 23rd for the 3DS, had performed well.
Fortunately, IGN managed to get Nintendo to reveal a few sales numbers, Kid Icarus included. Kid Icarus: Uprising sold over 135,000 copies in March in the U.S. Since the game was released on the 23rd, that accounts for about a week of sales.
Meanwhile, Mario Kart 7 sold another 118,000 copies in March, while Super Mario 3D Land sold 100,000. The two games are at 1.58 million and 1.98 million sold in the U.S. respectively. Finally, the Nintendo 3DS itself sold 225,000 units in March.