Worldwide tablet shipments grew to 76.9 million units in the fourth calendar quarter of 2013 (4Q13) according to preliminary data from the International Data Corporation (IDC) Worldwide Quarterly Tablet Tracker. The total represents 62.4% growth over the previous quarter and 28.2% growth over the same period a year ago. While the market's growth rates remain impressive, they're down dramatically compared to the year-over-year rates of the same quarter one year ago (87.1%) and indicate a significant slowing of the overall market.

For the full calendar year 2013, worldwide tablet shipments totaled 217.1 million units, which is up from 144.2 million units for the full year 2012 and represents a year-over-year growth rate of 50.6%.

"It's becoming increasingly clear that markets such as the U.S. are reaching high levels of consumer saturation and while emerging markets continue to show strong growth this has not been enough to sustain the dramatic worldwide growth rates of years past," said Tom Mainelli, Research Director, Tablets, at IDC. "We expect commercial purchases of tablets to continue to accelerate in mature markets, but softness in the consumer segment—brought about by high penetration rates and increased competition for the consumer dollar—point to a more challenging environment for tablets in 2014 and beyond."

Apple once again led the worldwide market for tablets, shipping 26 million units during the quarter, up from 14.1 million the previous quarter and 22.9 million in 4Q12. While the quarter represented the company's most successful on record, its year-over-year growth of 13.5% was well below the industry average. The numbers bring into focus the challenges the company faces as it attempts to grow its tablet business in markets outside of its traditional mature-market strongholds and in the face of continued success from competitors both large and small.

Apple saw its worldwide tablet market share for the quarter grow to 33.8%, up from 29.7% in the third quarter but down from its 38.2% share in the fourth quarter of 2012. Samsung retained its second-place spot on the strength of a wide portfolio of products and increased carrier support in markets like the U.S., grabbing an 18.8% share worldwide. That's down slightly from 18.9% the previous quarter, but up significantly from its 13% share a year ago. Rounding out the top five were Amazon (7.6%), ASUS (5.1%), and Lenovo (4.4%).

"Lenovo’s access to the Chinese whitebox manufacturing infrastructure has helped it drive more low-priced tablet products into the market, growing its share from just 1.3% in the same quarter last year," said Jitesh Ubrani, Research Analyst, Worldwide Quarterly Tablet Tracker. "The company's strength in emerging markets, and its increased market share in adjoining markets such as PCs and smartphones, makes it well positioned to see additional tablet gains in 2014."

To read the full IDC report, click here.