(Telecompaper) Worldwide tablet shipments soared by 75.3 percent to 52.5 million units in the fourth quarter of 2012, compared with 29.9 million units a year earlier, according to IDC. Shipments rose 74.3 percent versus 30.1 million units in the third quarter. The market was led by Apple with 22.9 million units shipped, 48.1 percent more than in the fourth quarter of 2011, giving it a 43.6 percent market share. Samsung's unit sales surged 263 percent to 7.9 million units, for a 15.1 percent market share, followed by Amazon, up 26.8 percent to 6 million units for an 11.5 percent share, Asus up 402.5 percent to 3.1 million units for a 5.8 percent share, Barnes & Noble down 27.7 percent to 1 million units for a 1.9 percent share, and others up 77.4 percent to 11.6 million units. Microsoft entered the market during the quarter with its Surface with Windows RT tablet, but failed to reach the top five after shipping fewer than 900,000 units.