Research firm IDC has published its estimates for the tablet market in both the final quarter of 2013, and for the year as a whole. On the latter front, it claims that 217.1m tablets shipped last year globally, up 50.6% from 2012’s 144.2m units. In Q4, meanwhile, worldwide shipments totalled 76.9m units, up 28.2% year-on-year. Reason for celebration? Actually, IDC is warning of a slowdown, particularly in the US. “It’s becoming increasingly clear that markets such as the US 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 IDC’s Tom Mainelli. Maybe tablets aren’t that annual upgrade cycle that Apple’s iPad may have led some people to believe… Talking of iPad, though, Apple accounted for 33.8% of tablets shipping in Q4 last year, according to IDC. That’s ahead of Samsung (18.8%) and Amazon (7.6%).