(Telecompaper) Amazon grew its turnover 22 percent to USD 21.27 billion in the fourth quarter of 2012, and its operating profit by 56 percent to USD 405 million. Operating margin growth in North America was partly driven by higher sales on its website by third parties, accounting for 39 percent of units purchased in the period. Net profit fell by 45 percent to USD 97 million in the fourth quarter. Company founder and CEO Jeff Bezos said the eBooks category grew by around 70 percent in 2012, while physical book sales only rose by 5 percent, the slowest December growth rate since Amazon opened for business 17 years ago. The company still built 20 warehouses last year. Amazon anticipates sales of USD 15-16.6 billion in the first quarter, up by 14-26 percent year-on-year. It expects to report a figure between an operating loss of USD 285 million and an operating profit of USD 65 million, compared to a USD 192 million operating profit in the first quarter of 2012.